Finding Mars from The Big Dipper (The Plough), August 2009 to July 2010

Find Mars in your Local Night Sky with AstroViewer®

Moon near Mars Dates, Sep 2009 to Dec 2010

Mars Meridian Transit Altitudes, 2001-2012

Mars Opposition Data, 2001-2012

 

Path of Mars from Aug 2009 to Jul 2010 (Copyright Martin J Powell 2009)

 

The path of Mars against the background stars of Gemini, Cancer and Leo from August 2009 to July 2010, shown at 10-day intervals. During this apparition, Mars describes a typical, Northward-facing loop, differing somewhat from the hybrid formation (half-loop, half-zigzag) of the 2007-8 period. A close-up of the planet's path through the M44 (Praesepe) star cluster is shown below. The star map applies to observers in the Northern hemisphere (i.e. North is up); for the Southern hemisphere view, click here (the Southern hemisphere chart should be used by observers situated south of the Tropic of Cancer [23½° North]). The Milky Way is shown in dark grey; the faintest stars shown on the map have an apparent magnitude of about +4.8. Printer-friendly versions of this chart are available for Northern and Southern hemisphere views. Astronomical co-ordinates of Right Ascension (longitude, measured Eastwards in hrs:mins) and Declination (latitude, measured in degrees North or South of the celestial equator) are marked around the border of the chart.

The Mars Apparition of 2009-2010 by Martin J Powell

Following superior conjunction on December 5th 2008 (when it passed directly behind the Sun) Mars emerged in the dawn sky in February 2009 as a relatively dim 'morning star', rising shortly before the Sun. Through the first half of 2009, the planet is best seen from the Southern hemisphere, although the planet's great distance and small apparent size during this period makes it a disappointing sight when observed through telescopes. For Northern hemisphere observers, viewing circumstances are poor throughout the first half of 2009, with Mars appearing low down in the Eastern sky at dawn. Seen from the Northern hemisphere, Mars does not become a prominently visible object until late July 2009, by which time the long summer twilight is starting to recede and the planet is rising about four hours before the Sun. Viewing circumstances improve for both hemispheres as 2009 progresses.

From early 2009 through to August 2009, Mars moves steadily Eastwards (direct motion) through the following constellations, slowly brightening as its distance from Earth reduces:

Date Range

Constellation

<----- Mid-Period ----->

Apparent Magnitude

Apparent

Diameter

(arcsecs)

Solar

Elongation

2009

Feb 1 to Feb 3

Sagittarius

+1.3

3".8

15º

Feb 3 to Mar 11

Capricornus

+1.2

4".0

20º

Mar 11 to Apr 15

Aquarius

+1.2

4".2

 27º

Apr 15 to May 1

Pisces

+1.2

4".4

33º

May 1 to May 4

 

Cetus

+1.2

4".4

35º

May 4 to May 31

Pisces

+1.2

4".4

37º

May 31 to Jul 2

Aries

+1.1

4".8

44º

Jul 2 to Aug 25

Taurus

+1.1

5".2

54º

Table showing the position and apparent magnitude of Mars for the early part of the 2009-2010 apparition. The magnitudes, diameters and solar elongations listed here refer to the middle of the period in question. Mars begins the apparition far to the South in Sagittarius, then ascends the ecliptic (heading Northwards) from Capricornus through to Taurus. In this and the tables which follow, the rising and setting directions of the constellations listed can be found by referring to the zodiacal constellation rise-set direction table.

On August 25th 2009, Mars crosses the boundary from Taurus, the Bull, into Gemini, the Twins. Mars brightens significantly from late September 2009 and its coloration begins to appear more distinct. On October 12th 2009, the planet enters Cancer, the Crab, the faintest constellation of the zodiac and therefore the least easy to identify. From late October 2009 through to mid-May 2010, city-dwellers, struggling to discern Cancer under light-polluted skies, will find Mars occupying the large, dark 'gap' in the night sky between Gemini and Leo; to find these two constellations from The Big Dipper (or The Plough), refer to the animation below.

The planet Mars in Gemini, December 2007

Mars in Gemini  The Red Planet last appeared bright in late December 2007; this photograph was taken about a week before it reached peak brightness, when it shone at magnitude -1.5. The planet reached opposition on Christmas Eve of that year (Move your cursor over the image to identify the stars, and click for a full screen picture).

From late October to early November 2009, Mars crosses the star cluster Messier 44 (M44 or NGC 2632) commonly known as Praesepe (pronounced 'pree-SEE-pee') which is visible to the naked-eye as a hazy patch of light (for more details, see below). City-dwellers will detect the cluster easily with binoculars when panning the area of the sky immediately around Mars.

On November 30th 2009, Mars enters Leo, the Lion, where it remains for the next six weeks. Mid-way through its vacation, on December 21st 2009, the planet reaches its Eastern stationary point, five degrees South of the star Alterf (Greek letter Lambda Leonis, mag. +4.3). The Red Planet returns to Cancer on January 10th 2010, now moving retrograde (East to West).

Mars reaches opposition (i.e. its brightest for this apparition) on the night of January 29th 2010. Note that, although opposition takes place on this date, Mars' closest approach to the Earth (at 0.6639 Astronomical Units or 99.33 million kms) takes place two days earlier - on January 27th 2010 - because of the planet's eccentric orbit.

At opposition, a planet is positioned directly opposite the Sun in the sky (rising around sunset and setting around sunrise) and is visible throughout the night. Its highest point in the sky is reached when it crosses the observer's meridian at local midnight (due South in the Northern hemisphere, due North in the Southern hemisphere). A list of maximum altitudes and directions of the planet at opposition for various latitudes is given in the table below.

With an apparent magnitude of -1.3 and a maximum apparent disk diameter of 14".1 (14.1 arcseconds, where 1 arcsecond = 1/3600th of a degree), Mars at this opposition is not as bright nor as large (when seen through a telescope) as it was at its previous opposition in December 2007, when the planet reached magnitude -1.6 and had an apparent diameter of 15".8. This is because, at the 2010 opposition, the planet is further away from the Earth than it was at the 2007 opposition.

At its next opposition in 2012, the Red Planet will be even further from the Earth, appearing smaller still (13".9) and fainter (mag. -1.2). At this time, Mars will be near the point in its orbit when it is most distant from the Sun (a point called aphelion); such oppositions are often referred to as aphelic oppositions (for more details, see below).

Date

Constellation

Apparent

Magnitude

Apparent

Diameter

(arcsecs)

View from

Earth

(0h UT)

(North up)

Distance (AU)*

Solar

Elongation

Illuminated

Phase

Central

Meridian

Longitude

(0h UT)

from Earth

from Sun

2009

 Aug 22

Tau

+1.0

5".6

View of Mars from Earth on August 22nd 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6589

1.4732

61º

89%

104°

Sep 1

Gem

+1.0

5".8

View of Mars from Earth on September 1st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6032

1.4859

65º

89%

007°

Sep 11

Gem

+0.9

6".1

View of Mars from Earth on September 11th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.5437

1.4989

68º

89%

270°

Sep 21

Gem

+0.8

6".3

View of Mars from Earth on September 21st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.4802

1.5119

72º

88%

174°

Oct 1

Gem

+0.8

6".6

View of Mars from Earth on October 1st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.4128

1.5250

76º

88%

078°

Oct 11

Gem

+0.7

7".0

View of Mars from Earth on October 11th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.3420

1.5379

81º

88%

341°

Oct 21

Cnc

+0.6

7".4

View of Mars from Earth on October 21st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.2679

1.5506

86º

88%

246°

Oct 31

Cnc

+0.5

7".9

View of Mars from Earth on October 31st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.1912

1.5630

91º

88%

150°

Nov 10

Cnc

+0.3

8".4

View of Mars from Earth on November 10th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.1127

1.5749

97º

89%

055°

Nov 20

Cnc

+0.1

9".1

View of Mars from Earth on November 20th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.0334

1.5864

103º

89%

320°

Nov 30

Cnc

-0.0

9".8

View of Mars from Earth on November 30th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.9551

1.5973

111º

90%

227°

Dec 10

Leo

-0.2

10".6

View of Mars from Earth on December 10th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.8797

1.6076

119º

92%

134°

Dec 20

Leo

-0.5

11".6

View of Mars from Earth on December 20th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.8099

1.6172

128º

93%

042°

Dec 30

Leo

-0.7

12".5

View of Mars from Earth on December 30th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7494

1.6261

139º

95%

311°

 2010

Jan 9

Leo

-0.9

13".3

View of Mars from Earth on January 9th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7022

1.6341

151º

97%

222°

Jan 19

Cnc

-1.1

13".9

View of Mars from Earth on January 19th 2010 at 0h UT (Image from NASA's Solar System Simulator v4.0)

0.6726

1.6413

164º

99%

134°

Jan 29

Cnc

-1.3

14".1

View of Mars from Earth at opposition on January 29th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.6641

1.6477

175º

100%

047°

Feb 8

Cnc

-1.1

13".8

View of Mars from Earth on February 8th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.6780

1.6531

166º

99%

320°

Feb 18

Cnc

-0.9

13".1

View of Mars from Earth on February 18th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7134

1.6576

153º

98%

232°

Feb 28

Cnc

-0.6

12".2

View of Mars from Earth on February 28th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7670

1.6611

142º

96%

143°

Mar 10

Cnc

-0.4

11".2

View of Mars from Earth on March 10th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.8347

1.6637

131º

94%

052°

Mar 20

Cnc

-0.1

10".3

View of Mars from Earth on March 20th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.9126

1.6653

121º

93%

321°

Mar 30

Cnc

+0.1

9".4

View of Mars from Earth on March 30th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.9974

1.6659

113º

91%

228°

Apr 9

Cnc

+0.3

8".6

View of Mars from Earth on April 9th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.0862

1.6655

106º

90%

134°

Apr 19

Cnc

+0.5

8".0

View of Mars from Earth on April 19th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.1771

1.6641

99º

90%

040°

Apr 29

Cnc

+0.7

7".4

View of Mars from Earth on April 29th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.2684

1.6617

93º

89%

305°

May 9

Cnc

+0.8

6".9

View of Mars from Earth on May 9th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.3588

1.6584

88º

89%

210°

May 19

Leo

+0.9

6".5

View of Mars from Earth on May 19th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.4475

1.6540

82º

89%

114°

May 29

Leo

+1.0

6".1

View of Mars from Earth on May 29th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.5335

1.6488

78º

89%

018°

Jun 8

Leo

+1.1

5".8

View of Mars from Earth on June 8th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6163

1.6426

73º

90%

281°

Jun 18

Leo

+1.2

5".5

View of Mars from Earth on June 18th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6956

1.6356

69º

90%

184°

Jun 28

Leo

+1.3

5".3

View of Mars from Earth on June 28th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.7708

1.6277

65º

91%

087°

Jul 8

Leo

+1.4

5".1

View of Mars from Earth on July 8th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.8418

1.6190

61º

91%

350°

Jul 18

Leo

+1.4

4".9

View of Mars from Earth on July 18th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.9083

1.6095

57º

92%

252°

* 1 AU (Astronomical Unit) = 149,597,870 kms (92,955,806 statute miles)

Table of selected data relating to the brighter part of the Mars apparition of 2009-10. The data is listed at 10-day intervals, corresponding with the dates on the star map. The Central Meridian Longitude (provided for telescopic observers) is the Martian longitude which appears at the centre of the disk when seen from the Earth at the time indicated (0h Universal Time, or 0h GMT). A Martian longitude map by Damian Peach showing the surface features can be seen at the BAA Mars Section website (note that the map is shown with South up, matching the inverted view seen through astronomical telescopes). For example, when CM = 290°, Syrtis Major appears at the centre of the disk. The Central Meridian Longitude increases by 14°.6 every hour, so this allowance should be applied for observations at other times (if the result is greater than 360°, subtract 360° to obtain the correct longitude). Those wishing to observe Mars telescopically should consider downloading the free 'Mars Previewer II ' software by Leandro Rios, available as a ZIP file at Sky & TelescopeThe data for the table was obtained from 'MegaStar', 'SkyGazer Ephemeris'  and 'Mars Previewer II' software and the Martian disk images were derived from NASA's Solar System Simulator v4. The Martian disks appear at the same scale as those in the Mars Opposition data table below.

Mars fades rapidly after opposition as its distance from Earth increases, but it remains visible for a further 10 months in the evening sky, slowly closing in on the setting Sun. Mars reaches its Western stationary point in Western Cancer, 7°.2 North-west of Asellus Borealis and 7°.7 South-west of Pollux, on March 11th 2010. The planet leaves Cancer and enters Leo once more on May 12th 2010, where it stays for a little over two months before entering Virgo on July 19th of that year.

Mars' furthest distance from Earth for this apparition (2.3793 AU or 356 million kms) is reached on January 7th 2011, when its apparent diameter is a mere 3".9 across. By December 2010, Mars becomes lost from view in the dusk twilight.

 

Date Range

Constellation

<----- Mid-Period ----->

Apparent Magnitude

Apparent

Diameter

(arcsecs)

Solar

Elongation

2010

Jul 19 to Sep 26

Virgo

+1.5

4".4

46º

Sep 26 to Oct 27

Libra

+1.5

4".0

30º

Oct 27 to Nov 8

Scorpius

+1.4

4".0

 24º

Nov 8 to Dec 3

 

Ophiuchus

+1.3

3".8

19º

Dec 3 to

Sagittarius

+1.2

3".8

10º

2011

 Jan 15

Table showing the position and apparent magnitude of Mars for the latter part of the 2009-10 apparition. The magnitudes, diameters and solar elongations again refer to the middle of the period in question. As the apparition draws to a close, Mars heads Southwards along the ecliptic, moving from Virgo through to Sagittarius, where the apparition had begun some 23 months previously.

Mars passes behind the Sun - at superior conjunction - on February 4th 2011. The 2011-2013 apparition begins soon afterwards, which will see Mars in the constellation of Leo when it next reaches opposition on March 3rd 2012.

 [Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]

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Finding Mars in the Night Sky, August 2009 to July 2010

From late August to mid-October 2009, when Mars is moving through Gemini, The Big Dipper (The Plough) can be used to locate Gemini using the method shown in the animation below.

From late October 2009 through to about mid-May 2010, when Mars is moving through Cancer, the planet will be found inside a triangle formed by the stars Regulus (in Leo), Castor (in Gemini) and Procyon (in Canis Minor). Throughout this period, Mars is brighter than any of the stars contained within this triangle, so observers in both town and city will spot Mars long before Cancer itself is identified.

Finally, from late May to mid-July 2010, when Mars is moving through Leo, The Big Dipper can be used to find Leo using the method shown in the animation below.

If Mars is some months away from opposition when it is observed, its coloration may not be immediately obvious to the naked eye; in which case, a pair of binoculars will help to reveal its trademark orange colour.

 

Finding Gemini, Cancer and Leo from The Big Dipper

The well-known asterism (star group) known as The Big Dipper (or The Plough) in Ursa Major (The Great Bear) can be used as a starting point to finding Gemini, Cancer and Leo in the night sky (provided these constellations are above the observer's horizon at the required time).

To find Leo, project the line between the stars Megrez (Greek letter Delta Ursae Majoris) and Phekda (Greek letter Gamma Ursae Majoris) in a Southward direction until you reach the bright star Regulus (Greek letter Alpha Leonis) as indicated in the animation.

To find Gemini, project the diagonal line between Megrez and Merak (Greek letter Beta Ursae Majoris) towards the South-west until you come across the two leading stars of The Twins, namely Castor (Greek letter Beta Geminorum) and Pollux (Greek letter Beta Geminorum).

Cancer can be found using the The Dipper or, alternatively, by using Gemini and Leo. Project the line formed by Alioth (Greek letter Epsilon Ursae Majoris) and Phekda towards the South-west, into the 'dark' region of sky between Gemini and Leo; the Cancer constellation is located about half-way between Castor and Regulus.

Note that this method primarily applies to Northern hemisphere observers. Southern hemisphere observers can only use this method if they are situated North of latitude 28° South (The Big Dipper is not wholly visible at latitudes further South than this). Observers at mid-Southern latitudes should instead use the AstroViewer Java applet below.

A diagram showing the lines pointing to Gemini, Cancer and Leo from The Big Dipper can be seen here.

Animation showing how to find Gemini, Cancer and Leo from 'The Big Dipper' or 'The Plough' asterism (Copyright Martin J Powell 2009)

 

In the final frames of the animation, Ursa Major (The Great Bear) appears with his head facing towards the East, as depicted by the late writer and illustrator H. A. Rey in the 1950s. Star atlases often show The Bear facing in the opposite direction (West), e.g. as illustrated here.

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Bright Stars, Nearby Stars and Open Star Clusters

From November 2009 to early April 2010, Mars is brighter than all of the stars shown on the star map. The four brightest stars shown are Procyon (Greek letter Alpha Canis Minoris, magnitude +0.4), Pollux (Greek letter Beta Geminorum, mag. +1.1), Regulus (Greek letter Alpha Leonis, mag. +1.3) and Castor (Greek letter Alpha Geminorum, mag. +1.6). Mars is brighter than both Regulus and Castor throughout the period, and is only exceeded in brightness by Procyon prior to November 2009 and after mid-April 2010. The planet is brighter than Pollux as it enters the star chart (late August 2009) and only becomes fainter than it after mid-June 2010.

Procyon, in the constellation Canis Minor (the Lesser Dog) is the eighth brightest star in the night sky and the fourth brightest Northern celestial hemisphere star. Procyon is a Greek name meaning 'before the dog', referring to the fact that it rises before the 'Dog Star', i.e. Sirius (Greek letter Alpha Canis Majoris, mag. -1.4, the brightest star in the night sky). Canis Minor contains little of interest for the binocular or telescopic observer, except for a few double stars. Procyon itself is interesting in that it has a companion white dwarf star (Procyon B), of very high density, orbiting the primary star (Procyon A) every 41 years. Procyon B is 11th magnitude and lies too close to Procyon A to be detectable in anything but professional telescopes; indeed, it was not discovered until 1896. Procyon is 11.4 light years distant (where 1 light year = 63,240 AU), meaning that it takes light 11.8 years to traverse the distance, and is one of the nearest stars to the Earth. Sirius is however closer still, at 8.6 light years and co-incidentally it also has a white dwarf companion.

Gemini's leading stars Castor and Pollux are named after the twins of Queen Leda of Sparta in ancient Greek mythology; the Romans identified them with the brothers Romulus and Remus who, according to ancient tradition, founded the city of Rome. The two stars are seperated by 4°.5, providing a useful reference for measuring angular distances in the night sky. The constellation's Western half is set against the backdrop of the Milky Way, so this region contains several open star clusters (groups of young stars within our galaxy which have been formed from the same nebulous cloud) and nebulae (interstellar clouds of gas and dust). The whole constellation also features numerous double stars and multiple stars.

Castor is part of a complex star system. The main star (Castor A) has a companion (Castor B, mag. +2.9) about 4".6 (4.6 arcseconds) away from it; a small telescope will be able to split the two. Larger telescopes will reveal a third star (Castor C or YY Geminorum) of ninth magnitude, some 70" away. Not visible in amateur telescopes is an additional companion star to each of these three stars, making Castor a sextuple star system. Castor and Pollux lie at distances of 52 light years and 34 light years from Earth, respectively.

Viewed from the orbiting Earth, whenever two celestial bodies appear to pass each other in the night sky (a line-of-sight effect) the event is known as a conjunction or an appulse. Conjunctions are generally considered more noteworthy when they involve two bright planets, however the term is equally applicable - although perhaps less visually spectacular - when they involve a planet and a star. Mars is in conjunction with bright (and moderately bright) stars on several occasions during the period indicated on the star chart; these will now be discussed, in chronological order.

Photograph of Cancer and the Northern section of Hydra, showing the path of the ecliptic (click for full-size picture)

Cancer and Northern Hydra  A photograph showing the region of the night sky which Mars passes through during the 2009-10 observing season. The asterism forming the head of the Water Snake is somewhat more obvious than Cancer itself (Move your pointer over the image to identify the constellations and click on the image for a full-size picture).

During the final days of August and into early September 2009, Mars passes close to three bright stars and one open star cluster, all situated towards the 'foot' of the Western Twin.

Gemini's Westernmost bright star is 1 Geminorum (mag. +4.1); Mars passes 0°.3 North of this star on August 27th 2009. Sir William Herschel discovered Uranus in the vicinity of this star in March 1781; the blue-green planet was then situated just across the border in Taurus.

A short distance North-east of 1 Geminorum is the open star cluster Messier 35 (M35 or NGC 2168). It can be glimpsed with the naked-eye on a dark, clear night as a small, misty patch of light. Mars passes 0°.8 South of the cluster on August 29th 2009. The cluster has an apparent diameter about the size of the Full Moon and it contains over 400 stars (!) It lies at a distance of about 2,800 light years from the Earth. Binoculars show a bright, elliptical glow with several stars, the cluster appearing somewhat 'doughnut-shaped' since there are considerably fewer stars at its centre. Small telescopes fitted with wide-field (low magnification) eyepieces show curving chains of stars from 8th to 12th magnitude. M35 is one of the more spectacular open star clusters in the night sky and astronomy authors have variously described its appearance as 'rich', 'beautiful', 'outstanding' and 'marvelous'!

The star Eta Geminorum (Greek letter Eta Gem, mag. +3.1v), also known as Propus or Tejat Prior (meaning 'forward foot') is both a double star and a variable star. It has a close companion star of 8th magnitude which orbits the primary star once every 500 years; medium or large telescopes are required to resolve the pair. Tejat Prior is a red giant which fluctuates in brightness between mags. +3.1 and +3.9 over the course of about 230 days. Mars passes 1°.1 North of Tejat Prior on August 31st 2009. Three days later (September 3rd) Mars passes 1°.0 North of Mu Geminorum (Greek letter Mu Gem, mag. +3.2v), or Tejat Posterior ('latter foot'). This is also a double star, having a ninth-magnitude companion positioned some 2' (2 arcminutes, where 1 arcminute = 1/60th of a degree) to the South-east of the primary, visible in small telescopes. The secondary star itself has a tenth-magnitude companion which requires larger telescopes to resolve.

On September 25th 2009, the Red Planet passes 0°.8 North of another double star, Wasat (Greek letter Delta Geminorum, mag. +3.5), a name which is Arabic for 'middle'. The primary star is creamy-white and its magnitude +8.2 companion is orange. This pair should be easy to split, however the great brightness difference between the two stars makes them difficult to split in smaller telescopes. Astronomer Clyde Tombaugh discovered Pluto near Wasat in February 1930, while he was examining photographic plates of the region which had been taken between January 23rd and 29th of that year.

Cancer, the Crab, is the faintest constellation of the zodiac and therefore the most difficult to see, particularly from urban and suburban locations, where the limiting magnitude (the faintest stars visible at the observer's zenith) may only be around +4.0. Cancer's five brightest stars form a shape reminiscent of the Greek letter lambda in lower case (Greek letter Lambda). The brightest star (mag. +3.5) has been incorrectly assigned the name Beta Cancri (Greek letter Beta Cnc) where it should technically have been classed as Alpha (Greek letter Alpha). The actual star carrying the designation Greek letter Alpha Cancri is named Acubens (meaning 'claws', mag. +4.3). It is a double star with an 11th magnitude companion; a small telescope will resolve them.

The star Iota Cancri (Greek letter Iota Cnc, mag. +4.0), at the Northern end of the Crab, is a double star with a magnitude +6.5 companion. The stars are seperated by a sizeable 30" (30 arcseconds) allowing the pair to be resolvable in 10x50 binoculars. Telescopes show the stars to be a pretty combination of gold and pale-blue.

Cancer contains two interesting open star clustersM44 (NGC 2632) is known as Praesepe or 'The Beehive Cluster' because of its binocular resemblance to a cloud of swarming bees. It is visible to the naked eye as a hazy patch of light at the constellation's centre but is much better seen through binoculars and telescopes. It lies at a distance of about 520 light years and is thought to be about 650 million years old. Binoculars show around 50 stars contained in a field of view roughly 80' (80 arcminutes) across. Small to medium-sized telescopes reveal about 75 stars visible down to about magnitude 12, whilst large telescopes show around 300 stars down to 17th magnitude. Because of Praesepe's large area (it is 95' across) telescopes need to be fitted with wide-field eyepieces in order to appreciate the full splendor of this cluster.

Praesepe is positioned a short distance North of the ecliptic (the apparent path of the Sun, which the Moon and planets follow very closely), so planets regularly pass across it in rather spectacular fashion. In 2009, Mars crosses the cluster between October 31st and November 2nd - a pretty sight when seen through binoculars.

The path of Mars through M44 in late October/early November 2009

M67 open star cluster in Cancer

 

Open Star Clusters in Cancer

Two examples of open star clusters which can easily be seen in binoculars: (Left) M44 (NGC 2632, commonly known as Praesepe or the Beehive Cluster) and (Right) M67 (NGC 2682) in the Southern region of the constellation. Mars passes through (in front of) M44 in late October/early November 2009 (move your pointer over the image - or click on it - to see the track of the planet, marked at 0h UT on each date). Mars later passes 1°.2 to the North of the cluster, while moving retrograde, in mid-April 2010. Stars in the pictures are visible down to about magnitude +8.3. North is up and East is to the left in both pictures (Photos Copyright Martin J Powell, 2005-6)

The following day (November 3rd 2009), Mars passes mid-way between the stars Asellus Borealis (Greek letter Gamma Cancri, mag. +4.7) and Asellus Australis (Greek letter Delta Cancri, mag. +3.9). Bizarrely, the names mean 'northern donkey' and 'southern donkey' respectively. This probably relates to the fact that M44 is sometimes referred to as 'The Manger' in reference to the Nativity story; in this case the donkeys are considered to be feeding at the Manger. Mars again passes between these two stars on April 19th 2010, although on this occasion it is positioned closer to Asellus Borealis, being 0°.8 to the South of it.

M67 (NGC 2682) is located 1°.7 to the West of Acubens. It is smaller and denser than M44 and is just beyond naked-eye visibility. There are over 300 stars in the cluster, which lies about 2,600 light years away. Binoculars show it as a small, hazy patch; small telescopes reveal about 20 stars down to 11th magnitude and medium-sized telescopes show around 50 stars down to 12th magnitude. With an estimated age of 5 billion years, this is one of the oldest known open star clusters, containing several red giant stars nearing the end of their lives.

Leo is perhaps the most recognisable of the zodiac constellations, and one of the few which bears a resemblance to the animal it is supposed to represent - a crouching Lion. The Lion's head and 'mane' are an asterism of its six Westernmost stars commonly called the Sickle of Leo, which is shaped like a backward question-mark [A backwards question-mark!] At the base of the question-mark is Leo's brightest star, Regulus. It is also the closest bright star to the ecliptic, lying about 0°.5 degrees away from it. One consequence of this is that the star is regularly passed by the Moon and planets - indeed, Mars passes 0°.9 North of it on June 6th 2010. The fact that the name Regulus and the word 'Regal' are similar is no coincidence; Regulus is Latin for 'Little King', reflecting an ancient belief that it controlled the affairs of the heavens. It was given the name in the sixteenth century by the famous Polish astronomer Nicolaus Copernicus.

Approximately mid-way between the 'upper hind leg' stars Coxa (Greek letter Theta Leonis, mag. +3.9) and Greek letter Iota Leonis are a pair of galaxies about 37 million light years away. M65 (NGC 3623, mag. +9.5) and M66 (NGC 3627, mag. +8.8) are positioned 20' (0°.3) apart and are among the brightest of many dozens of galaxies which exist in the constellation of LeoM65 and M66 appear relatively bright and elliptical through small telescopes, orientated in a North-South direction. They are just discernible through binoculars in dark, moonless skies as faint, circular hazy patches of light.

Finally, on July 12th 2010, Mars passes 1°.0 South of the star Sigma Leonis (Greek letter Sigma Leo, mag. +4.0) at the 'foot' of Leo's hind leg. One week later, the planet moves from Leo into Virgo and out of the star chart coverage.

Other constellations on the chart contain objects of interest which observers may wish to track down, and these will now be discussed briefly.

The Rosette Nebula (NGC 2237) imaged by John Lanoue

The Rosette Nebula (NGC 2237) is a diffuse nebula situated in the constellation of Monoceros. The star cluster NGC 2244 is at its centre (Image: Wikipedia, with permission of John Lanoue)

The constellation Monoceros, the Unicorn, is positioned between Procyon and Sirius. The fact that it is outshone by these two luminaries somewhat detracts from the fact that it contains a number of interesting star clusters and nebulae. Perhaps the most interesting of these is the Rosette Nebula (NGC 2237), an emission nebula which glows by emitting light from the radiation of the young, hot stars contained within it. The Rosette is about 4,700 light years distant and appears much like a beautiful pink carnation in long-exposure photographs. Alas, it is too faint to be seen in binoculars and small telescopes; medium and large telescopes are only likely to reveal the nebula's brightest regions when seen under very dark skies. More obvious to binocular and small telescope observers will be the star cluster at the nebula's centre (NGC 2244) comprising numerous stars of sixth magnitude and fainter.

In the Southern part of Monoceros is the open star cluster M50 (NGC 2323), about 2,600 light years distant. Its brightest stars can be seen in binoculars but a telescope is needed to resolve its 150 or so stars.

The Christmas Tree (NGC 2264) is an open star cluster with an associated nebulosity known as the Cone Nebula. The nebula is too faint to be seen in amateur telescopes, but the cluster's leading star, fifth-magnitude S Monocerotis (or 15 Mon), situated at the Northern end (base) of the 'Tree', is easily seen in binoculars, along with about 20 other stars down to about ninth magnitude. The 'Christmas Tree' appears inverted to Northern hemisphere observers and upright to Southern hemisphere observers. Appropriately, the Christmas Tree cluster crosses the observer's meridian (due South in the Northern hemisphere, due North in the Southern hemisphere) at local midnight around Christmas time.

Leo Minor (the Little Lion or Lion Cub), situated between Leo itself and Ursa Major, is fainter even than Cancer. It contains no stars brighter than magnitude +3.8 and there are no deep-sky objects (star clusters, nebulae and galaxies) to view in moderate-sized telescopes or binoculars. Because of a 19th century error when assigning star labels, this constellation has no star named Alpha (Greek letter Alpha) Leonis Minoris, although this should technically have been assigned to its brightest star, 46 Leonis Minoris.

Lynx, like Leo Minor, is a relatively recent constellation, having been introduced in the 17th-century by the Polish astronomer Johannes Hevelius. It bears no resemblance to a lynx and was in fact so-named because, as Hevelius put it, "only the lynx-eyed would be able to see it"! Lynx contains numerous double stars and multiple stars of interest to the amateur observer.

Hydra, the Water Snake, is the largest constellation in the sky, extending across 95° of celestial longitude; only its Northern section is included in the star chart. Hydra snakes its way between no less than ten constellations, starting just South of Cancer and ending just to the South of Libra. Hydra's brightest stars are all found in its Northern half, at the top of which is an asterism of six stars which form the distinctive shape of the Water Snake's head.

Close to Hydra's Western border with Monoceros is the open star cluster M48 (NGC 2548). It is about 2,000 light years away and comprises some 80 stars, covering an area about the same apparent size as the Full Moon. Under dark skies, the cluster can just be seen with the naked-eye as a hazy spot and around 50 stars of the group can be resolved in binoculars. Telescopes reveal several yellowish stars along with mostly white ones, some of them double.

 

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 Moon near Mars Dates, September 2009 to December 2010

The Moon is easy to find, and on one or two days in each month, it passes Mars in the sky. Use the following tables to see on which dates the Moon passes near the planet between September 2009 and December 2010:

Date Range

(World)

Conjunction (Geocentric)

Solar Elong.

Moon Phase

Date & Time

Sep. & Dir.

2009

Sep 13/14

Sep 13, 15:59 UT

.1 S

69°

Waning Crescent

Oct 11/12

Oct 12, 01:27 UT

.1 N

81°

Waning Crescent

Nov 8/9

Nov 9, 06:00 UT

.5 N

96°

Last Quarter

Dec 6/7

Dec 7, 02:45 UT

.5 N

116°

Waning Gibbous

Moon near Mars dates for the period from August 2009 to December 2010. The Date Range shows the range of dates worldwide (allowing for Time Zone differences across East and West hemispheres). Note that the Date, Time and Separation of conjunction (i.e. when the two bodies are at the same celestial longitude) are measured from the Earth's centre (geocentric) and not from the Earth's surface (times are Universal Time [UT], equivalent to GMT). The Sep. & Dir. column gives the angular distance (separation) and direction of the planet relative to the Moon, e.g. on April 22nd 2010 at 09:27 UT, Mars is positioned 4°.6 North of the Moon's centre. The Moon Phase shows whether the Moon is waxing (between New Moon and Full Moon), waning (between Full Moon and New Moon), at crescent phase (less than half of the lunar disk illuminated) or gibbous phase (more than half but less than fully illuminated).

Date Range

(World)

Conjunction (Geocentric)

Solar Elong.

Moon Phase

Date & Time

Sep. & Dir.

2010

Jan 2/3

Jan 3, 11:31 UT

.8 N

114°

Waning Gibbous

Jan 29/30

Jan 30, 08:06 UT

.6 N

175°

Full

Feb 25/26

Feb 26, 05:08 UT

.3 N

143°

Waxing Gibbous

Mar 25/26

Mar 25, 13:58 UT

.5 N

117°

Waxing Gibbous

Apr 21/22

Apr 22, 09:27 UT

.6 N

97°

Waxing Gibbous

May 19/20

May 20, 11:48 UT

.2 N

82°

First Quarter

Jun 17/18

Jun 17, 18:39 UT

.9 N

69°

Waxing Crescent

Jul 15/16

Jul 16, 04:44 UT

.2 N

58°

Waxing Crescent

Aug 13/14

Aug 13, 17:22 UT

.9 N

48°

Waxing Crescent

Sep 10/11

Sep 11, 08:22 UT

.0 N

39°

Waxing Crescent

Oct 9/10

Oct 10, 01:51 UT

.5 N

30°

Waxing Crescent

Nov 7/8

Nov 7, 22:11 UT

.6 N

22°

Waxing Crescent

Dec 6/7

Dec 6, 21:45 UT

.5 N

14°

Waxing Crescent

Lovers' Conjunction

On August 13th 2010, during the closing months of Mars' 2009-10 apparition, an interesting grouping of the Moon and planets takes place in the evening sky. This is the author's simulation of how the event might appear from the island of Tenerife in the Canary Islands (Islas Canarias) around 10 pm Local Time (22:00 Western European Summer Time or 21:00 UT), some two hours after local sunset.

Looking West, the three-day-old Moon, Venus (mag. -4.3) and Saturn (mag. +0.9) form a line spanning 13°.6 across which appears almost parallel with the local horizon. Mars (mag. +1.5) is positioned 2°.7 above (Northeast) of the trio, having just passed conjunction with the Moon (see table above). The group are situated in central Virgo at the time, a short distance to the South of the star Porrima (mag. +3.6). Mercury (mag. +0.6) is also visible for a short while earlier that evening, low down in the West some 16° to the West of Saturn (below and to the right of Saturn in the picture).

The Moon, Venus and Saturn sink below the horizon, within a five minute period, around 23:00 Local Time. Mars, now much dimmer and distant than in previous months, sets about nine minutes later.

Seen from the rest of the world, the angle of the Moon and the planets in relation to an observer's horizon will vary according to the observer's latitude (Tenerife is situated at 28° 20' North). The position of the Moon itself in relation to the planets will also vary depending upon the local time at which the grouping is observed.

(Move your pointing device over the image to identify the stars and planets and click on the image for a full-sized picture).

The picture was based on a photograph at Wikipedia.

Lovers' Conjunction, Tenerife

The Moon moves relatively quickly against the background stars (in an Eastward direction, at about its own angular width [0º.5] each hour, or about 12º.2 per day) and because it is relatively close to the Earth, an effect called parallax causes it to appear in a slightly different position (against the background stars) when seen from any two locations on the globe at any given instant; the further apart the locations, the greater the Moon's apparent displacement against the background stars. Therefore, for any given date and time listed in the table, the Moon will appear closer to Mars when seen from some locations than others. For this reason, the dates shown in the table should be used only for general guidance.

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Finding Mars in Your Local Night Sky using AstroViewer®

Where in the night sky should I look for Mars tonight? In which direction and how high up will it be?

From late August 2009 to mid-July 2010, when Mars is moving through Gemini, Cancer and Leo, The Big Dipper (The Plough) can be used to locate the planet using the method shown in the animation above.

The location of a planet (or any other celestial body) in your local night sky depends upon several factors: the constellation in which it is positioned, your geographical latitude and longitude, the local season and the date and time at which you observe. To find a planet in the night sky at any particular date and time, we must know two things: a direction in which to look along the observer's horizon (eg. Southeast, East-Southeast) and an angle to look above the horizon (known as altitude or elevation).

The following Javascript program can be used to help find Mars (and any other planets) in your night sky throughout the year:

'Mini-AstroViewer' Java applet

For additional information on the fully-functional

version of the program, see here.

Mini-AstroViewer® is an easy-to-use Java applet which shows the positions of the celestial bodies in the night sky for any location on the globe at any time of the year (Javascript must be enabled in your browser for the program to function).

To activate the program, click on the button below (the program will open in a pop-up window).

Please enable JAVATM to use the Mini-AstroViewer night sky map.

The default location is New York, USA. To select your own location and then find Mars, refer to the 'Finding Mars ..' box below.

An animated tutorial showing how to locate a planet in the night sky using Mini-AstroViewer® can be seen here.

  • The applet also shows the positions of the planets in their orbits, viewed from a point in space far above the Solar System (click on the tab marked 'Solar System' at the top of the applet; use the left-hand scroll bar to zoom out).

Finding Mars in Your Own Night Sky using Mini-AstroViewer®

Sun, Moon and planet colours as they appear in AstroViewer®. The program displays the Moon in its correct phase

To set your own location, click on the 'Location' button and click on your approximate position on the pop-up world map. If you know your precise latitude and longitude, you can refine your position by pressing the left/right and up/down arrows to move the cross-hair in 1° increments (to find your latitude and longitude, visit the Heavens Above website, select your country and enter the name of your nearest town or city using the 'Town Search' facility). Having plotted your geographical co-ordinates, click 'OK' and the night sky over your own location will appear in the window, valid for the current time, which is displayed in UT (Universal Time, equivalent to GMT). The applet will initialise displaying the current UT time according to your browser's clock and Time Zone settings (if you would prefer to have the Local Time displayed, use the fully-functional version of the program at Astroviewer.com).

The red circle represents the horizon around you; the lower half of the display represents the part of the sky you are facing. The centre of the circle is the point directly above your head (known as the zenith). The ecliptic (the path along which the Sun, Moon and planets will be found) is marked by a red dashed line, passing as it does through the zodiac constellations. The blue dashed line marks the apparent position of the celestial equator, which arcs across the sky from the due East point on the horizon to the due West point. The program plots stars down to magnitude +5.0.

The bottom scroll bar rotates the horizon view, allowing for a view in any compass direction; the left-hand scroll bar zooms the sky in or out, and the right-hand scroll bar pans up (to the zenith) or down (to the horizon) whenever the view has been zoomed.

Mini-AstroViewer demonstration

Animation showing how to locate a planet in the night sky using Mini-AstroViewer® (in this case, Jupiter). A more detailed animation showing how to use the program can be seen here.

Infomation on a celestial body can be viewed by clicking on the object (in the case of a planet, its magnitude, distance, elongation and apparent diameter). Note that if the elongation (its angular distance from the Sun as seen from the Earth) is less than about 15°, the planet will not be visible because it is too near the Sun. Remember that local twilight can affect the visibility of a particular planet, even at elongations greater than 15°, making observation difficult or even impossible. This particularly applies throughout the local summer months at higher latitudes.

To locate Mars, first see if it is above the horizon at the time you are requesting. If it is visible within the circle, move the bottom scroll bar left or or right to rotate the image until the planet is positioned on the vertical red line (the altitude scale). Zoom in to the area using the left-hand scroll bar where necessary (see animation opposite).

The direction of Mars at the requested time will be indicated at the bottom (W, SW, etc). The altitude of the planet (its angle above the horizon) can be read off on the altitude scale (it is marked at 10° intervals). Hence if it is three notches up, its altitude is 30° at the displayed time (to understand how to determine a planet's altitude in the night sky, refer to the two diagrams below). If Mars' altitude is less than about 10° it may be difficult to see because of the dimming effect of the Earth's atmosphere and, in town and city locations, the effects of light pollution or skyglow.

If Mars is not shown within the circle, it is below the horizon and you will have to wait until after it next rises before you can see it (provided it is not too near the Sun). To find when it next rises, click the 'hours forward' button (Forward in time button) repeatedly until the planet appears over the eastern horizon, then note down the time and direction this occurs. By clicking the 'minutes/hours forward' buttons (Forward in time button), Mars can then be tracked across the sky for the remainder of the night (using direction and altitude) as described above.

If Mars rises in daylight (i.e. if the Sun is already above the horizon), you will have to wait until dusk to see it - in which case, 'fast forward' to a time shortly after sunset, then note down the time and direction.

The same method can also be used to find any of the visible constellations in your night sky.

Diagram showing how altitude (or elevation) is determined for a celestial body in the night sky

 

Direction and Altitude diagram

Angular altitude (or elevation) is measured as 0º at the horizon (when an object is at the point of rising or setting), 45º when 'half way up the sky' and 90º when directly above the observer's head (at the zenith). In the above picture, the bright star has an an altitude of about 60º (i.e. it is "60º high").

Using direction and altitude to find a star or planet in the night sky - in this case, the star/planet is in the Southeast (SE) at an altitude of 20º.

 

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The Current Night Sky over Montréal, QC, Canada  Flag of Canada

Would you like to see your own town or city shown here?

 

Requested locations may appear on another planet page (see links below) depending upon the number of requests received by the author at any given time.

A list of the night sky locations currently displayed on this website can be seen on the main Naked-eye planets page.

The graphic shows the sky at the location indicated when this page was loaded in your browser; if several minutes have since passed, click the 'Refresh' button at the top of your browser (or press the F5 key) to see the current sky.

The Night Sky location displayed here is periodically changed by the website author.

Additional AstroViewer® Information

Mini-AstroViewer® is a lightweight version of AstroViewer®, an interactive night sky map that helps you find your way in the night sky quickly and easily. Due to its intuitive interface, it is well suited to beginners in astronomy.

The fully functional, free-to-use version can be accessed at the AstroViewer® website. It has additional features such as a Local Time display, a planet visibility chart for any selected location, a 3D Solar System map, the ability to store user-generated world locations, a 'Find Celestial Body' facility, printing and language options and greater flexibility in the night sky display (see details here).

A fully-functional version for offline use can be obtained upon the purchase of a license key, following the download and installation of a test version.

AstroViewer® is produced by Dirk Matussek.

Current night sky over Montreal

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Mars Meridian Transit Altitudes, 2001 to 2012

Mars is one of only two Solar System planets whose surface details can be seen through modest-sized telescopes; the other being Mercury, whose small size and low altitude (angle above the horizon) often precludes a clear view. For the naked-eye observer, apart from the increased likelihood of obstruction from trees and buildings, a planet's low altitude is generally of little consequence, however for the telescopic observer, high altitude is essential in order to minimise the effects of turbulence, atmospheric dimming and light pollution (skyglow) which prevails near the horizon. Consequently, telescopic observers consider high altitude transits (when a celestial body crosses the observer's meridian, reaching its highest point in the sky) as more favourable than low altitude transits. As a general rule, telescopic observation is best done when a celestial body's altitude is greater than about 30°; hence observation in the couple of hours after rising or before setting is best avoided, unless there is no other alternative.

Mars' meridian transit altitude (as seen from any given point on Earth) varies as the planet drifts Eastwards through the zodiac from one opposition to the next. The meridian transit altitude at which an observer sees a planet is determined not only by the constellation in which the planet is positioned at the time, but also by the observer's latitude. As a result, certain apparitions are more favourable to observers in one hemisphere than to observers in the opposite hemisphere.

In general, high-Northerly oppositions (in Taurus or Gemini) are best seen from the Northern hemisphere and high-Southerly oppositions (in Scorpius, Ophiuchus, Sagittarius or Capricornus) are best seen from the Southern hemisphere. Mars' last most Northerly opposition took place in Gemini in December 2007, when observers at mid-Northern latitudes saw the planet transit at around 60° to 70° high in the sky, providing optimal conditions for viewing through telescopes. Mid-Southern hemisphere observers fared rather worse, the planet transiting at around 20° to 30° highMars' next most Northerly opposition will be in December 2022, when it will be positioned in Taurus (its subsequent opposition in January 2025 will also be high, on the Gemini/Cancer border).

Mars' last most Southerly opposition took place in Ophiuchus in June 2001, when observers at mid-Southern latitudes saw the planet transit at around 70° to 80° high in the sky; mid-Northern hemisphere observers saw it transit at just 20° to 30° high. Mars' next most Southerly opposition will be in July 2018, when it will be positioned in Capricornus.

After the 2001 opposition, observing circumstances for Northern hemisphere observers gradually improved as the planet ascended the ecliptic at each successive opposition. Following its high opposition in Gemini in 2007, the planet is now beginning to descend the ecliptic once more, a process which will continue through its next four oppositions in Leo (2012), Virgo (2014), Scorpius (2016) and finally Capricornus (2018).

Southern hemisphere observers, having experienced a few rather poor oppositions altitude-wise (in 2005, 2007 and 2010), will see observing circumstances improve over the coming years, the planet appearing further South (i.e. at a higher transit altitude) at each successive opposition.

Opposition Date

Meridian Transit Altitude and Transit Direction (due North or due South)

Lat 60°N

Lat 50°N

Lat 40°N

Lat 30°N

Lat 20°N

Lat 0°

Lat 15°S

Lat 25°S

Lat 35°S

Lat 45°S

2001 June 13

3°.5 (S)

13°.5 (S)

23°.5 (S)

33°.5 (S)

43°.5 (S)

63°.5 (S)

78°.5 (S)

88°.5 (S)

81°.5 (N)

71°.5 (N)

2003 August 28

14°.2 (S)

24°.2 (S)

34°.2 (S)

44°.2 (S)

54°.2 (S)

74°.2 (S)

89°.2 (S)

80°.8 (N)

70°.8 (N)

60°.8 (N)

2005 November 7

45°.9 (S)

55°.9 (S)

65°.9 (S)

75°.9 (S)

85°.9 (S)

74°.1 (N)

59°.1 (N)

49°.1 (N)

39°.1 (N)

29°.1 (N)

2007 December 24

56°.7 (S)

66°.7 (S)

76°.7 (S)

86°.7 (S)

83°.3 (N)

63°.3 (N)

48°.3 (N)

38°.3 (N)

28°.3 (N)

18°.3 (N)

2010 January 29

52°.1 (S)

62°.1 (S)

72°.1 (S)

82°.1 (S)

87°.9 (N)

67°.9 (N)

52°.9 (N)

42°.9 (N)

32°.9 (N)

22°.9 (N)

2012 March 3

40°.2 (S)

50°.2 (S)

60°.2 (S)

70°.2 (S)

80°.2 (S)

79°.8 (N)

64°.8 (N)

54°.8 (N)

44°.8 (N)

34°.8 (N)

 

Meridian Transit altitudes of Mars at successive oppositions from 2001 to 2012, as seen from a variety of latitudes. The planet's best (brightest) oppositions take place when it is positioned in Aquarius, as it was in 2003. During these times Southern hemisphere observers benefit from a high transit altitude; conversely, observers at mid-Northern latitudes must contend with less-than-ideal transit altitudes (< 35°). Observing circumstances improved for Northern hemisphere observers after the planet's 2001 opposition (when it was positioned at a high-Southerly declination in Ophiuchus) but they are now beginning to worsen once more. However, the Martian disk itself has been shrinking since 2003 (see Mars Opposition section below).

 

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Mars Opposition Data, 2001 to 2012

The varying transit altitude of Mars at each opposition is not the only factor which affects the ability to see the planet's surface details through telescopes; there is also the question of its hugely varying apparent size as seen from the Earth. This is the result of the planet's eccentric orbit, which brings it closer to the Earth at some oppositions than at others.

A planet's closest point to the Sun in its orbit is known as its perihelion, and its furthest point from the Sun is called its aphelion. Whenever a planet's opposition occurs close to - or at - its perihelion or aphelion point, it is often referred to as a perihelic opposition or aphelic opposition. Mars' perihelic and aphelic oppositions are particularly significant because its apparent size is considerably different in each case.

Opposition Date

Constellation

Declination

Apparent

Magnitude

Apparent Diameter (arcsecs)

View from

Earth

(North up)

% of

Max.

Size

Distance (AU)*

from Earth

from Sun

2001

June 13

 

Oph

-26°.5

-2.4

20".5

Mars at opposition in 2001 (Image from NASA's Solar System Simulator v4.0)

80

0.4558

1.4709

2003

August 28

Aqr

-15°.8

-2.9

25".1

Mars at opposition in 2003 (Image from NASA's Solar System Simulator v4.0)

98

0.3728

1.3811

2005

November 7

Ari

+15°.9

-2.3

20".0

Mars at opposition in 2005 (Image from NASA's Solar System Simulator v4.0)

78

0.4700

1.4609

2007

December 24

Gem

+26°.7

-1.6

15".8

Mars at opposition in 2007 (Image from NASA's Solar System Simulator v4.0)

61

0.5929

1.5758

2010

January 29

Cnc

+22°.1

-1.3

14".1

Mars at opposition in 2010 (Image from NASA's Solar System Simulator v4)

55

0.6644

1.6481

2012

March 3

Leo

+10°.2

-1.2

13".9

Mars at opposition in 2012 (Image from NASA's Solar System Simulator v4)

54

0.6740

1.6645

 

Opposition Data for Mars from 2001 to 2012. The Declination is the angle of the planet to the North (+) or South (-) of the celestial equator at the time of the planet's opposition. The angular disk diameter of the Red Planet at opposition has been shrinking significantly since its 2003 opposition. Mars' next aphelic opposition will take place in Leo in 2012; the planet will cross the aphelion point in its orbit about two weeks before opposition day. The Martian disk images were derived from NASA's Solar System Simulator v4 and are shown at the same scale as those in the August 2009 to July 2010 data table above.

Mars' brightest and best oppositions (perihelic oppositions) occur in groups of two or three which repeat in a cycle of about 16 years, when it is closest to the Earth (about 35 million miles/56 million kms distant). In the opposition of August 2003, when Mars was in Aquarius, the planet came closer to the Earth than it had been for almost 60,000 years; this was largely due to the fact that it reached the perihelion point in its orbit just two days after its opposition date. As seen from the Earth, the apparent equatorial diameter of the Martian disk then reached a sizeable 25".1 (25.1 arcseconds). The next perihelic opposition of Mars will take place in July 2018, in Southwestern Capricornus, when it will attain an apparent diameter of 24".2 and shine at magnitude -2.8.

In contrast, Mars' next aphelic opposition in 2012 will see the planet's apparent diameter attaining just 13".9, a little over half of its perihelic opposition value. This is by far the greatest apparent size variation of any of the superior planets at opposition.

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The Naked-eye appearance of Mars

Naked Eye Planet Index

Planetary Movements through the Zodiac

Positions of the Superior Planets:

Jupiter, 2009-2011

Saturn, 2006-2013

Uranus, 2006-2018

Neptune, 2006-2023

Pluto, 2006-2022

Current Position of the Sun and the Brighter Naked-Eye Planets (Star Map)


Web Rings

The Mars Webring

The Mars Ring

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Credits

 


Copyright © Martin J. Powell  June 2009



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