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The orbit of Saturn shown at two/three year intervals between the years 1993 and 2020 AD. The orbit of the Earth is seen close to the centre, marked at various dates by a blue-green globe (the orbits are not shown to scale). The dates in blue are the dates of Saturn's opposition to the Sun, i.e. when the planet is closest to the Earth and appears at its brightest for the year. The images in the grey circles show how the planet appears from the Earth (orientated with Celestial North at the top). The points of Saturn's perihelion (i.e. its closest point to the Sun) and aphelion (its most distant point from the Sun) are also marked. The constellation in which Saturn appears, as seen from the Earth, is shown in green. The First Point of Aries is the 'zero point' from which the longitudes of the planets are measured (diagram based on a graphic by space artist David A Hardy). |
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Animation showing the varying aspect of Saturn's rings at various opposition dates from 1993 to 2020, with additional orbital and observational details. The image is shown with Celestial North up (note that astronomical telescopes will normally show images inverted). Saturn images adapted from NASA JPL's Solar System Simulator ('SPACE') |
Saturn's rings contribute a great deal to its brightness, and in fact, from the vantage point of the Earth, they are not always fully on view. About every 13 to 16 years, the rings are edgewise-on to the Earth's line-of-sight, when they are only seen as a thin line in telescopes - or sometimes not at all - and the planet appears much dimmer in the sky. Saturn takes a little less than 29.5 years to orbit the Sun, and during this time we see the rings from different angles.
The rings were wide open in 2002-3 and Saturn's Southern hemisphere is currently tipped in our direction. The rings have been closing up in recent years, showing a narrower and narrower aspect, with Saturn becoming rather dimmer at each successive opposition, and the rings will appear edge-on to the Earth in September 2009 (although the planet will appear very close to the Sun at this particular time). They will then slowly open up again and be fully on view some eight years later (October 2017), when Saturn's Northern hemisphere will be tipped our way.
Note that when the rings are wide open (i.e. when Saturn is brightest) the planet is seen in the constellations of Taurus or Gemini (when its Southern hemisphere is facing Earth) or in Scorpius, Ophiuchus or Sagittarius (when its Northern hemisphere faces Earth). Edge-on ring aspects occur when the planet is on the Aquarius/Pisces border (when oppositions take place around September) or in Leo (oppositions taking place around March).
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Where is Saturn now?
Having spent the period from July 2005 to August 2006 in the constellation of Cancer, Saturn crossed the boundary into Leo on 30 August 2006. This diagram shows the apparent path of the planet through to late 2009. Periods of non-visibility (i.e. when the planet/constellation passes behind the Sun as seen from the Earth) are shown as a dashed line. Note that by the time Saturn reaches the tail-end of the Lion (i.e. South of the star Denebola) the rings will be seen edgewise-on to our line of sight (this diagram applies to the Northern hemisphere; for the Southern hemisphere view, click here). Printer-friendly versions of this chart are available for Northern and Southern hemisphere views. |
Like the other solar system planets, Saturn's orbit is somewhat elliptical, which means that its apparent size at opposition varies slightly throughout its 29.5 year orbit. When it is closest to the Sun (at perihelion), it lies some 9.03 Astronomical Units (AU) from the Sun; when furthest away (aphelion) it is 10.06 AU from the Sun (where 1 AU = 149,597,870 km or 92,955,807 statute miles). At perihelic oppositions, Saturn is some 743 million miles (1,197 million kms) from the Earth, whilst at aphelic oppositions it lies some 1027 million miles (1,654 million kms) from the Earth.
Saturn reaches opposition every 378 days, i.e. about 13 days later in each successive year.
Moon near Saturn Dates, October 2007 to December 2008
On one or two days in each month, the Moon can be used as our celestial guide to help in locating Saturn in the sky. Use the following table to determine on which dates to see the Moon in the vicinity of the planet:
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Moon near Saturn dates for the period from October 2007 to December 2008. 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 given in Universal Time [UT], equivalent to GMT). 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). |
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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 Saturn when seen from some locations than from others. For this reason, the dates shown in the table should be used only for general guidance.
Positions of the Superior Planets:
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Mars, 2007-2008 |
Jupiter, 2006-2008 |
Uranus, 2006-2018 |
Neptune, 2006-2023 |
Pluto, 2006-2022 |
Current Position of the Sun and the Brighter Naked-Eye Planets (Star Map)
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Saturn and How to Observe It (Astronomers' Observing Guide) Julius L. Benton, Jr. |
The Complete Idiot's Guide to Astronomy Christopher De Pree & Alan Axelrod |
NightWatch: A Practical Guide to Viewing the Universe Terence Dickinson "The best handbook for the beginning astronomer" |
Bang! The Complete History of the Universe Brian May, Patrick Moore & Chris Lintott |
Out There: The In-Depth Story of the Astronaut Love Triangle Case that Shocked America Diane Fanning |
Tourists in Space: A Practical Guide Erik Seedhouse |
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Credits
Copyright © Martin J. Powell, Nov 2005 with amendments Sep 2007; minor update Jan 2008
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(Main Index) |
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