MARS IN OPPOSITION: ONE FOR THE RECORD BOOKS
On 27th August, Mars will be at its closest to Earth for almost 60,000 years. On that date, the Red Planet will approach to within 34,646,418 miles (55,758,006 km) - 145 times the distance of the Moon.
The last time the two planets were so close our ancestors were living in caves and struggling to survive the extreme conditions of the Ice Age. Who knows what will have happened by the time they are as near again - 284 years into the future?
WHEN AND WHERE TO SEE MARS
Mars is now in the constellation Aquarius and is readily recognised because it is already the brightest object in the night sky (apart from the Moon). Instantly recognisable by its brilliance and orange-red colour, it will remain easy to spot for several months, low in the sky somewhere between the southeast and the southwest. (Exactly where depends on the date and time.)
Currently, Mars rises at about 11 pm (BST) but it comes up a few minutes earlier each night. Future rising times are 10 pm on 7 August, 9 pm on 21 August and 8 pm on 4 September. About 5 hours after it has risen, Mars reaches its highest point above the horizon - an altitude of about 23 degrees as seen from London - and lies due south.
BRIGHTER THAN THE STARS
At its peak brightness, Mars will reach magnitude -2.9, far outshining the brightest star, Sirius (magnitude -1.5). It will remain brighter than Sirius until mid-October. Venus is the only planet that can appear brighter, but Venus will not be visible again until December.
THE CLOSEST OF CLOSE ENCOUNTERS
Earth and Mars are rather like two runners going around a racetrack in lanes at different speeds. Mars travels around the Sun about one and a half times farther away than Earth on average and takes 687 days to make a circuit compared with Earth's 365 days. Roughly every 26 months, Earth overtakes Mars on the inside. When this happens, there's a close encounter between Earth and Mars and the two planets line up in space with the Sun. This orbital rendezvous is called an OPPOSITION of Mars, because the Sun and Mars are on opposite sides of Earth.
If the orbits of Earth and Mars were circles, Mars would be the same distance from Earth at every opposition. But the orbits are actually ellipses (oval-shaped), with the Sun offset from the centre. Mars, more so than Earth, follows a very non-circular orbit, so its distance from the Sun varies by 26.5 million miles (42.4 million km). This means that the distance between Earth and Mars at an opposition can be anything between about 35 million miles (56 million km) and 63 million miles (100 million km).
Because Mars's orbit is so elliptical, the time when Mars and Earth are closest and the actual opposition - when Sun, Earth and Mars are in a direct line - do not quite coincide. This year's opposition is on 28 August, a day later than closest approach.
Every 15 - 17 years, there is an opposition of Mars when the Red Planet is not far from its closest point to the Sun - its 'perihelion'.
TAKING A CLOSER LOOK
Mars is a small planet, roughly half the size of Earth. At its closest, it appears little more than half the size of Jupiter, or similar in size to a large crater on the Moon.
To see markings on its surface, you ideally need at least a 6 inch (15 cm) telescope. With a magnification of 40 when at its closest, Mars would appear about the same size as an orange seen with the naked eye across the length of a tennis court. You could see it was an orange but that's about all - it would be quite small.
To see any markings and the famous polar ice caps, a higher magnification is needed, if the telescope is good enough. Unfortunately, detailed observing will not be very easy from the UK at this opposition because Mars is so low in the sky.
It is now spring in Mars's southern hemisphere and the ice cap at the south pole is tilted towards Earth. As the atmosphere warms and the thin air begins to stir, dust storms frequently occur. Huge storms can sometimes shroud large areas of the planet, hiding the giant volcanoes and other surface features.
NOTES FOR EDITORS:
On 27th August at 10.51 BST (9.51 GMT) Mars will be closer to Earth than at any time since the year 57,617 BC - 59,619 years ago. It won't be as near again until 28th August 2287.
However, it is not too unusual for Mars to come almost as close. In 1924, for example, it was only 12,500 miles (20,000 km) farther away and to ordinary observers the planet looked just the same as it will this year.
UK National Astronomy Week 2003 (23 - 30 August) has been selected to reflect the time when Mars will be at its closest to Earth and when public interest will be at its highest. During that week, Mars will rise at about 9 pm BST and will be high enough to observe reasonably well by about 10.30 pm, about 11° above the horizon. This may not be the ideal time to observe it, as it will mean a late night for many people, and it will be higher in the sky later in the year, but this is the time most people will want to see it and the media attention will be at its peak.
MEMORABLE MARS MINUTIAE
Dr. Jacqueline Mitton,
Royal Astronomical Society Press Officer
Tel: +44 (0)1223-564914
Expertise: Where and when to see Mars.
Royal Astronomical Society Press Officer (Space Science).
Tel: +44 (0)1483-268672
Expertise: Mars missions and exploration.
Dr. Andrew Ball,
Open University,Milton Keynes.
Tel: +44 (0)1908-659596
Expertise: Planetary missions (except Beagle 2), Soviet/Russian space activities, missions to Near Earth Objects and comets.
Dr. Monica Grady,
National History Museum, London (from 26 August).
Tel: +44 (0)207-942-5709
Expertise: Mars and life on Mars, meteorites, asteroids, comets and impacts.
Professor Barrie Jones,
Open University,Milton Keynes.
Tel: +44 (0)1908-653229
Expertise: Martian atmosphere and volatiles, life on Mars, history of ideas about life on Mars.
Dr. Paula Martin,
University of Cambridge.
Tel: +44 (0)1223-333318
Expertise: Martian interior, surface processes and magnetic anomalies.
Professor Peter Read,
University of Oxford (from 28 July).
Tel: +44 (0)1865-272082
Expertise: Martian meteorology and climate.
Dr. David Rothery,
Open University,Milton Keynes.
Tel: +44 (0)1908-652124.Mobile: (0)7986-260-256
Expertise: Volcanology and planetary sciences, including Beagle2 landing site.
FURTHER INFORMATION ABOUT OBSERVING MARS:UK National Astronomy Week:
British Astronomical Association (Mars Section):
Sky & Telescope:
Approaching Mars (NASA Science News for June 18, 2003):
Mars Dust Storm (NASA Science News for 9 July 2003):
Issued by Jacqueline Mitton and Peter Bond, RAS Press Officer.