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The path of Jupiter against the background stars of Capricornus, Aquarius and Pisces from January 2009 to May 2011, with positions marked at the start of each month. Periods of invisibility (i.e. when the planet is too close to the Sun, or passes behind it) are indicated by a dashed line; hence the planet became lost from view (in the evening sky) in early January 2009 and became visible again (in the morning sky) in mid-February 2009. The chart shows the changing shape of a planet's apparent looping formation as it moves through the zodiac. After crossing the ecliptic (heading Southwards) in 2008, when Jupiter described a zig-zag formation in Sagittarius, Jupiter describes a hybrid formation (half loop, half zig-zag) in 2009, followed by a conventional, Southward-facing loop in 2010. 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 Capricorn [23½° South]). The Milky Way is shown in dark grey; the faintest stars 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 from the First Point of Aries) and Declination (latitude, measured in degrees North or South of the celestial equator) are marked around the border of the chart. |
The Position of Jupiter in the Night Sky, 2009 to 2011 by Martin J Powell
Throughout 2008, Jupiter was seen in the constellation of Sagittarius, the Archer, where it had been situated since late 2007 (for details, see the 2006-8 page). The planet entered Capricornus, the Sea Goat, in early January 2009; its entire 'hybrid' loop formation was described within Capricornus, close to the constellation's Eastern border. Jupiter then proceeds Eastwards (direct motion) and enters Aquarius, the Water Carrier, in early 2010; it passes behind the Sun during its passage through this constellation and so is not visible for much of its time there. By the time Jupiter emerges in the dawn sky in late March 2010, it is fast approaching the border with Pisces, the Fishes, which it enters in early May of that year. The planet's Southward-facing loop is mostly described within this constellation, making a brief return to Aquarius from mid-October to mid-December 2010, during which time it reaches its Western stationary point. The planet then resumes Eastward motion, re-enters Pisces and crosses the celestial equator (heading Northwards) in early February 2011. Jupiter briefly 'escapes' the zodiac, heading into the non-zodiac constellation of Cetus (pronounced 'SEE-tus'), the Whale, for a 12-day period from late February into early March 2011, before re-entering Pisces once more. Three months later - in June 2011 - Jupiter leaves Pisces when it crosses the boundary into Aries, the Ram.
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Jupiter in Virgo, 2005 Jupiter was situated in the constellation of Virgo when this picture was taken in January 2005. Jupiter (then magnitude -2.0) greatly outshone Spica, the brightest star in Virgo (magnitude +1.2) which is seen at the bottom left of the picture. The planet will return to this position in the sky in late 2016, i.e. after it has completed one Jovian orbit (11.8 Earth years) (Move your pointer over the image to identify the stars, and click for a full screen picture). |
Jupiter reaches opposition to the Sun (when it is closest to the Earth and brightest in the sky for the year) every 398.9 days on average, i.e. about 33½ days later in each successive year. For the period covered by the above star map, oppositions take place on August 14th 2009 and September 21st 2010. Around opposition, the planet is due South at local midnight in the Northern hemisphere (due North at local midnight in the Southern hemisphere).
Jupiter's 2010 opposition is interesting for two very different reasons. Firstly, it is the planet's brightest and best opposition of its entire 11.8-year orbit, the planet reaching perihelion (its closest point to the Sun, at 4.95 Astronomical Units or 740 million kms) just six months later, in March 2011. Secondly, it takes place on the same day as that of Uranus, the opposition times of the two planets being just five hours apart (see section Triple Conjunctions below).
Superior conjunction (when Jupiter passes behind the Sun as seen from the Earth) takes place on January 24th 2009, February 28th 2010 and April 6th 2011. The planet is not visible from Earth for about two weeks on either side of these dates.
The apparent magnitude of the planet during the period of the star chart is -2.8 (at opposition in 2009) and -2.9 (at opposition in 2010). At superior conjunction, the magnitude falls to -1.9 (in 2009), -2.0 (in 2010) and -2.1 (in 2011).
The apparent size of the planet (i.e. its angular size as seen from the Earth, measured in arcseconds, where 1 arcsecond = 1/3600 of a degree) at opposition is 48".9 (in 2009) increasing to 49".9 (in 2010).
Note that, because of the planet's rapid rotation speed, Jupiter's disk appears as an oblate spheroid through telescopes and high-magnification binoculars (i.e. it appears flattened at the poles and bulged at the equator). The dimension given above is the apparent equatorial diameter of the planet; its apparent polar diameter is about 6.5% less.
[Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]
Triple Conjunctions
During the 2009-2011 period, Jupiter is involved in two triple conjunctions with planets (i.e. three close passes of the same two planets within a single apparition); the first was with Neptune in 2009 (near the Capricornus/Aquarius border) and the second with Uranus in 2010-11 (in Pisces). For those who have not yet glimpsed these faint outer gas giants, the 2009-11 period offers good opportunities to find them with binoculars via a short 'star hop' from Jupiter. Details of the Jupiter-Neptune triple conjunction (with a finder chart) can be found here; details of the Jupiter-Uranus triple conjunction can be found on the Uranus page (which includes a finder chart and an animation of the conjunction).
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Bright Stars , Nearby Stars and Deep-Sky Objects
Throughout
the period of the star chart, Jupiter is considerably brighter than any of the stars shown.
The brightest stars on the chart are all situated in non-zodiac constellations.
The brightest star
shown is Fomalhaut (
PsA or Alpha Piscis Austrini, magnitude
+1.2) in Piscis Austrinus (or Piscis Australis) - the Southern
Fish, the only constellation in the night sky which has two official names in use. Fomalhaut is
a blue-white star, 22 light years
distant, whose name derives from the Arabic for 'the fish's mouth';
on older star charts, it is the destination of the stream of water which
is poured by Aquarius. With its Southerly declination (angle relative
to the celestial equator) of -30°, Fomalhaut is
difficult to view from latitudes North of about 55° North and is not visible
at all North of 60° North. Observers at these higher latitudes can only see
it during the
late summer and early autumn months, for
a couple of hours each night, low down near the Southern horizon.
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Also occupying this rather
visually barren region of the night sky, to the North-east of Fomalhaut, is
Deneb Kaitos or
Diphda (
Cet or Beta Ceti, magnitude +2.0), the brightest star of the constellation
Cetus, the Whale. Its name is Arabic
for 'the Southern branch of the tail', i.e. the tail-end of the Whale.
The
stars Markab (
Peg or Alpha Pegasi, mag.
+2.5) and Algenib
(
Peg or Gamma Pegasi, mag. +2.8v) in Pegasus (the
Winged Horse) form the Southern corners of the Great
Square of Pegasus
- four medium-bright stars of a near-perfect square just to the North of the Circlet
of Pisces.
The other stars of the Great
Square are
Sirrah
(
Peg or Delta Pegasi, mag. +2.0) and Scheat (
Peg or Beta Pegasi, mag. +2.4v). Sirrah is also
confusingly referred to by the name Alpheratz (
And or Alpha Andromedae) since it is technically situated across
the border in Andromeda.
The
brightest zodiac constellation star on the chart is Deneb Algiedi or
Deneb Algedi (
Cap or Delta Capricorni,
mag. +2.9v) in the tail of Capricornus.
Jupiter
described its 2009 loop just to the North of this star, passing 1°.7
from it (while retrograding)
on July 29th of that year, and 1°.8 from
it on December 20th (moving direct). At opposition on August 14th 2009,
Jupiter,
Deneb Algiedi and Nashira (
Cap or Gamma Capricorni, mag. +3.6) formed a small, near-equilateral triangle at the tail of the Sea Goat.
Just
over
4° to the West
of Deneb Algiedi is the fainter star 
Cap
(Iota Capricorni, mag. +4.2). Jupiter was in the vicinity of this star from late September of 2009, through October (when
it reached its Western stationary point and then resumed direct motion) and
into early November. The planet passed
18' (0°.3) to
the North of Cap on
September 24th 2009 and 22' (0°.3)
to the North of it on November 1st 2009; both of these events were visible in
the evening sky and were easily contained within the field
of view of
telescopes fitted with low-magnification eyepieces.
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Also contained within the star chart are a few deep-sky objects (objects beyond our Solar System) which are worthy of mention since they can be seen through binoculars and small telescopes.
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Stargazing with Binoculars Robin Scagell & David Frydman |
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Aquarius contains two of the most interesting planetary nebulae in the night sky. The term is a misleading one since they are neither planets nor nebulae! In fact, a planetary nebula is a dying star whose shells of ejected material are heated and illuminated by the ultraviolet radiation of the star itself. The stars are typically in the red giant phase of their life, which later contract into white dwarfs. Because of the various forms in which the ejected material takes - and the varying angles at which they are presented to the Earth's line-of-sight - planetary nebulae provide us with some of the most spectacular sights in the night sky, though larger telescopes are required to fully appreciate their structural details.
Planetary nebulae were so-named by the English (but German-born) musician and astronomer William Herschel in the late 18th century; his term described the objects' telescopic appearance, though of course their true physical nature was unknown at the time.
The
first noted
planetary nebula of interest in Aquarius
can be found within the region of dim stars to the South-west
of the star Skat ( Aquarii, mag. +3.3).
The Helix Nebula (NGC
7293, mag.
+7.3) is the nearest and brightest planetary to the Earth, being at an
estimated distance of 300 light
years (where 1 light
year = 63,240 AU).
It is visible in binoculars as a pale, rounded glow when seen under
dark skies; it has been described as resembling a 'smoke-ring'. Since it is
so close, it appears as one of the largest planetaries in the sky, covering
an area about 0°.25 across, or about half the apparent size of the Full
Moon. Telescopes fitted with low-power (wide field) eyepieces show a circular
misty patch, with some structural detail visible within the nebulosity; it appears
grey, sadly lacking the brilliant coloration often seen in observatory photographs.
The use of a nebula
filter (which
blocks out light
pollution but allows the emission wavelengths of nebulae to pass through) helps to increase the contrast of the nebula against the background
sky, subsequently making it easier to see.
The second (rather less spectacular) planetary within the Aquarian boundary lies about 1°.3 West of the star v Aquarii (Nu Aquarii or 13 Aqr, mag. +4.5). Through binoculars, the Saturn Nebula (NGC 7009, mag. +8.0) appears as little more than a faint spot of light, at the limit of visibility. Small telescopes show it to be non-stellar in appearance, elliptical in shape with a greenish hue. Large telescopes reveal two faint extensions (called ansae) on opposite sides of the planetary, giving it a passing resemblance to the famous ringed planet after which it is named. This planetary is thought to be around 2,500 light years away; the central star which is responsible for the surrounding nebula is magnitude +12.8 and even through large telescopes is difficult to see.
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Deep-Sky Objects in Aquarius, imaged by the Hubble Space Telescope Three examples of deep sky objects which can be glimpsed in binoculars and small telescopes: (Left) the Helix Nebula (NGC 7293), (Centre) the Saturn Nebula (NGC 7009) and (Right) the globular cluster M2 (NGC 7089) (Images by NASA/ESA). The beautiful colours so evident in the planetary nebulae unfortunately cannot be seen through telescopes because they are too faint to be detected by the naked-eye - a situation which has been likened to viewing flowers in the night-time. Long-exposure photographs taken with digital/CCD cameras attached to telescopes will however reveal some of the coloration. A highly detailed, zoomable image of the Helix Nebula can be seen at the HST's European site and a short video showing its likely morphology can be seen on YouTube. |
About
five degrees North of Aquarius' brightest star Sadalsuud ( Aquarii, mag. +2.9)
and eight degrees West
of Sadalmelik ( Aquarii, mag. +3.0) is the globular
cluster Messier
2
(M2 or
NGC 7089, mag. +6.4). Globular
clusters are dense concentrations of stars, all of which are about
the same age and chemical composition. The number of stars in a globular cluster
can lie anywhere between 10,000 and several million (!) and they are
amongst the oldest objects in the universe, being perhaps 10 billion years old.
M2
appears as a large, bright glow in binoculars and some may even be able to spot
it faintly with the naked-eye under truly dark skies. Telescopes show a pretty
concentration of stars of around 13th magnitude and fainter; individual stars
can be difficult to resolve in the stellar haze. The globular has an apparent
diameter of 13' (13 arcminutes, where 1 arcminute = 1/60th of a degree)
and it lies about 50,000 light years distant, in the outer halo of
the Milky Way galaxy.
The difficulty in viewing nebulae, globular clusters and galaxies through binoculars and small telescopes demonstrates an important point regarding the quoted apparent magnitudes of such deep sky objects. The apparent magnitude of the Helix Nebula, for example, is normally listed in astronomical catalogues at around +7.0 - potentially within easy reach of most binoculars - however this is a somewhat misleading figure because it refers to the magnitude the planetary nebula would have if it were a single point of light (i.e. like a star). In reality a planetary nebula is an extended object (the Helix Nebula measures about 12' by 10'). As well as the apparent magnitude, some authors, when giving brightness values for objects such as galaxies, nebulae and planetary nebulae, also include the object's surface brightness, i.e. its apparent magnitude allowing for the fact that it is spread over an area of the sky (this is usually the magnitude per square arcminute). The surface brightness of the Helix Nebula works out at about magnitude +13 (almost as faint as Pluto!) which more accurately reflects its faintness in the sky - and explains why it is such a difficult object to see. Consequently, observers should not be disappointed if they fail to spot it.
Jupiter Transit Altitudes, 2005 to 2011
Jupiter is the largest of the Solar System planets and it can show considerable detail even through modest-sized telescopes. A major factor determining the likelihood of seeing a clear telescopic image is the altitude (angle above the horizon) of a planet at the time of observation. 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.
Jupiter's meridian transit altitude (as seen from any given point on Earth) varies from one year to the next in the course of its 11.8-year journey through the zodiac constellations. Its most Northerly point is attained in Gemini (around 23½° North of the celestial equator) then - some six years later - its most Southerly point is attained in Sagittarius (around 23½° South of the celestial equator). In the intervening years, the planet lies somewhere between these two extremes.
The meridian transit altitude at which an observer sees a planet depends not only upon the constellation in which the planet is positioned at the time, but also upon 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 the 2007-8 period, observers at mid-Northern latitudes saw Jupiter at its lowest meridian transit altitude for some twelve years, as the planet traversed the Southernmost constellations of the zodiac. Observing circumstances for Northern hemisphere observers gradually improve from 2009, as the planet begins to ascend the ecliptic once more, moving North-eastwards through Capricornus, Aquarius and Pisces.
Conversely, during 2007-8, observers in mid-Southern latitudes saw Jupiter high up in the sky when it reached meridian transit (due North in the Southern hemisphere) providing optimal viewing conditions for telescopic observers. Although the coming years will see the transit altitude reduce from these latitudes, it remains sufficiently high (mostly above 50°) so as not to adversely affect telescopic observations.
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Apparition Period |
Opposition |
Meridian Transit Altitude at Opposition and Transit Direction (due North or due South) |
Alt. Range |
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Date |
Con. |
Dec. |
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 |
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2005/6 |
2006 May 4 |
Lib |
-14°.7 |
15°.3 (S) |
25°.3 (S) |
35°.3 (S) |
45°.3 (S) |
55°.3 (S) |
75°.3 (N) |
89°.7 (N) |
79°.7 (N) |
69°.7 (N) |
59°.7 (N) |
± 3°.3 |
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2006/7 |
2007 June 5 |
Oph |
-21°.9 |
8°.1 (S) |
18°.1 (S) |
28°.1 (S) |
38°.1 (S) |
48°.1 (S) |
68°.1 (S) |
83°.1 (S) |
86°.9 (N) |
76°.9 (N) |
66°.9 (N) |
± 1°.5 |
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2008/9 |
2008 July 9 |
Sgr |
-22°.5 |
7°.5 (S) |
17°.5 (S) |
27°.5 (S) |
37°.5 (S) |
47°.5 (S) |
67°.5 (S) |
82°.5 (S) |
87°.5 (N) |
77°.5 (N) |
67°.5 (N) |
± 1°.2 |
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2009/10 |
2009 Aug 14 |
Cap |
-15°.2 |
14°.8 (S) |
24°.8 (S) |
34°.8 (S) |
44°.8 (S) |
54°.8 (S) |
74°.8 (S) |
89°.8 (S) |
80°.2 (N) |
70°.2 (N) |
60°.2 (N) |
± 4°.0 |
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2010/11 |
2010 Sep 21 |
Psc |
-2°.1 |
27°.9 (S) |
37°.9 (S) |
37°.9 (S) |
47°.9 (S) |
57°.9 (S) |
77°.9 (S) |
77°.1 (N) |
67°.1 (N) |
57°.1 (N) |
47°.1 (N) |
± 5°.2 |
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Transit altitudes of Jupiter at successive oppositions from 2005 to 2011, as seen from a variety of latitudes. The Declination (Dec.) is the angle of the planet to the North (+) or South (-) of the celestial equator at the time of the planet's opposition. The Altitude Range is the approximate altitude variation over the course of the apparition, e.g. for the 2005/6 apparition at latitude 40° North, the transit altitude of Jupiter ranged from (35°.3 - 3°.3) = 32° to (35°.3 + 3°.3) = 38°.6. Note that, from 2009, Jovian transit altitudes improve for Northern hemisphere observers but worsen slightly for Southern hemisphere observers. |
What are the best and worst case scenarios regarding Jupiter's transiting altitude? Northern hemisphere observers have recently witnessed their worst case scenario (and Southern hemisphere observers have witnessed their best) in the 2007-8 observing season, when Jupiter passed through the Southernmost zodiac constellations; details of this are shown in the table above. Jupiter will reach its most Northerly point along the ecliptic in June 2013, when it enters Gemini (its 2013/14 'zig-zag' path will be described to the South-west of Gemini's two luminaries Castor and Pollux). Observers at mid-Northern latitudes will then see the planet transit at around 60° to 70° high in the sky (best case scenario); mid-Southern hemisphere observers will fare rather worse, the planet transiting at around 20° to 30° high (worst case scenario).
Moon near Jupiter Dates, 2010
The Moon is easy to find, and on one or two days in each month, it passes Jupiter in the sky. Use the following table to see on which dates the Moon is in the vicinity of the planet:
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Moon near Jupiter dates for 2010 (no entries are given for February or March because in these months Jupiter is too close to the Sun - and therefore not visible - when the Moon is nearby). The Date Range shows the range of dates worldwide (allowing for Time Zone differences across East and West hemispheres). Note that the dates, times and separations at conjunction (i.e. when the two bodies are at the same Right Ascension) 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 July 4th at 00:58 UT, Jupiter is 7°.1 South of the Moon's centre. The Moon Phase shows whether the Moon was 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). |
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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 Jupiter when seen from some locations than from others. For this reason, the dates shown in the table should be used only for general guidance.
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How to Photograph the Moon and Planets with your Digital Camera (Patrick Moore's Practical Astronomy Series) Tony Buick |
What If The Earth Had Two Moons? And Nine Other Thought-Provoking Speculations on the Solar System Neil F. Comins |
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Position of Jupiter's Four Brightest Moons
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Jupiter's four brightest moons (satellites) - namely Ganymede (magnitude +4.6 at opposition), Io (+5.0), Europa (+5.3) and Callisto (+5.6) - can readily be seen through telescopes or steadily-held binoculars. The moons are seen to change their position in relation to each other, along the planet's equatorial plane, from one night to the next. In fact, their motion can be detected in the space of just a few hours.
Because of their low magnification, binoculars may have some difficulty detecting Io since it is the closest of the four moons to the planet; it never lies more than three Jupiter-diameters away. Europa is easier, but Ganymede is the easiest of the four to see. Callisto moves furthest away from the planet, but it is also the faintest of the four.
Due to Jupiter's shallow axial tilt (3º.1 to the plane of its orbit), the Jovian moons appear to present a more-or-less linear motion when seen from the Earth (this is in contrast to, say, Saturn with its relatively high axial tilt (26º.7 ), which causes its moons to mostly follow apparent elliptical paths around the planet when viewed from the Earth - see Saturn's moon positions). Approximately every six years, when the Earth passes through Jupiter's equatorial plane, the Jovian moons are seen to become involved in mutual occultations (where the moons pass in front of each other) and mutual eclipses (where a moon's shadow falls upon another moon). Numerous mutual events took place in 2009 and they continue (to a lesser extent) into 2010.
The following Flash program initialises displaying the positions of the moons at the current Universal Time (UT, which is equivalent to GMT) based on your computer's clock and Time Zone settings:
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The Positions of Jupiter's four brightest satellites in relation to the planet (the graphic requires the Adobe Flash Player plug-in to display correctly). Binocular and terrestrial telescope users in the Northern hemisphere should use the default 'Erect Image' (North up, East to the left) setting; Southern hemisphere observers using this equipment will need to click on the 'Inverted' (North down, West to the left) button. Users of astronomical telescopes in the Northern hemisphere will need to use the 'Inverted' option to match the view in their telescope, whilst those in the Southern hemisphere should use the default ('Erect Image') setting. The 'Mirror Reversed' button applies to astronomical telescopes with a star diagonal attached. Enter the required values for Date (in the form mm/dd/yyyy) and Time and click on 'Recalculate' to see the position of the moons for any date and time between January 1st 1900 AD and December 31, 2100 AD. The Timezone offset from UT is determined by the settings in your web browser. Other details shown are the planet's apparent magnitude, its angular size (in arcseconds), its distance from the Sun (in Astronomical Units) and the planet's System II Longitude (the Jovian longitude of the central meridian, i.e. the imaginary line through the centre of the planet's disk from pole to pole). Since Jupiter's outer layers are gaseous, the planet does not rotate as a solid body; in fact the equatorial region (known as System I ) makes one rotation in 9h 50m 30s whilst the rest of the planet (System II) rotates once in 9h 55m 40s. The Great Red Spot is located in System II, at a latitude of about 22° South. Pressing the 'Display' button generates a list of Jovian satellite phenomena for the selected date - namely transits (when a moon or its shadow passes across the planet's disk), occultations (when a moon passes behind the planet's disk) and eclipses (when a moon enters Jupiter's shadow). All of these events can be observed in telescopes. The next three transit times of the Great Red Spot (GRS) - i.e. when it crosses the planet's central meridian - are also listed, the GRS itself being displayed on the graphic. Note that the accuracy of these times is dependant upon the Jovian longitude of the GRS, which slowly drifts over time. By default, the program uses a longitude of 98°, however this is now incorrect and the value must be updated in order to provide accurate transit times. As of mid-2009, the longitude of the GRS was approximately 138°, so this value should be entered in the 'GRS Longitude' box and the timings recalculated by pressing the 'Display' button. The current longitude of the GRS will normally be given on Sky & Telescope's Great Red Spot page, where a list of transit times for the current year is also provided. Times of all events in the program are given in Universal Time (UT) which is equivalent to Greenwich Mean Time (GMT). The 'Jupiter's Moons' program by John Bartucci is available as a standalone, executable (exe) file which can be downloaded from the The Wilderness Center Astronomy Club website. |
Finding Jupiter in Your Local Night Sky
Where in the night sky should I look for Jupiter tonight? In which direction and how high up will it be?
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).
Use the following Javascript program to help find Jupiter in your night sky throughout the year:
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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). The default location is New York, USA. To select your own location and then find the planets, refer to the 'Finding The Planets ..' box below. An animated tutorial showing how to locate a planet in the night sky using Mini-AstroViewer® can be seen here.
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Finding Jupiter in Your Own Night Sky using Mini-AstroViewer®
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.
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 Jupiter, 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 Jupiter 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 Jupiter's altitude is less than about 10° it might 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
Jupiter 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 ( If Jupiter 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.
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The Current Night Sky over
Seoul,
South Korea |
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. |
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Positions of the Superior Planets:
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Mars, 2009-2010 |
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)
Credits
Copyright © Martin J. Powell February-July 2009, revised December 2009
) 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 (
