How long until the next Mars Opposition?
Race Around the Sun
Mars was closest to us on August 27, 2003, some 34.65 million miles away. The planet averages about 140 million miles away from Earth. Like a full moon it was face-on to Earth and opposite the Sun on the 28th (opposition). It was the closest to the Sun (perihelion) in its orbit on August 30. The reason Mars was so close was that Earth was about the farthest away from the Sun in its orbit at the time that Mars was nearing its closest point to the Sun.
Mars Express, a NASA and the European Space Agency joint mission, with its June, 2003,
launch took advantage of the close pairing of the two planets. Another mission, Mars Exploration Rovers launched in June and July of 2003 sent 2 rovers to explore our neighboring planet. Unlike the 22 pound
Mars Pathfinder rover, these robot geologists weigh almost 400 pounds and are about as big as a large office desk.
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The diagram at right shows that the orbit of Mars is not quite a perfect circle. As Earth passes the planet about every 2 years the distance between them varies as the dates show. Note that the orbit of Mars at 1 year, 320 days, is not quite double Earth's 365 day orbit so the opposition points are always changing. The next three oppositions will be November 7, 2005, December 24, 2007 and January 29, 2010.
What Can We See?
In June, 2003, you were able to spot a bright, reddish object on the eastern edge of the constellation Capricornus, the Sea Goat, and over the next few months follow it into Aquarius. See the August
star map for the location of these constellations and also
Sky and Telescope Magazine's online
Interactive Sky Chart. In August, binocular viewers were able to make out a round disk rather than a point of light like a star. Telescope viewers were able to see light and dark spots and some of the polar cap. The planet was really bright at about -3 magnitude but in the northern hemisphere was low on the horizon so any unsteady seeing conditions blurred the image. Tens of thousands of people around the world viewed Mars individually or at large Mars gazing "parties". The
Astronomical League has a
Mars Observer's Handbook available on their website. Find out if a local astronomy club is having a public Mars viewing event on the next Mars opposition (in 2005) by checking the
Member Society page in late 2005.
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This Hubble Space Telescope image of Mars shows some of the features that may be seen although not in as much detail.
"Frosty white water ice clouds and swirling orange dust storms above a vivid rusty landscape reveal Mars as a dynamic planet in this sharpest view ever obtained by an Earth-based telescope. The Earth-orbiting Hubble telescope snapped this picture on June 26, when Mars was approximately 43 million miles (68 million km) from Earth -- its closest approach to our planet since 1988. Hubble can see details as small as 10 miles (16 km) across. Especially striking is the large amount of seasonal dust storm activity seen in this image. One large storm system is churning high above the northern polar cap [top of image], and a smaller dust storm cloud can be seen nearby. Another large duststorm is spilling out of the giant Hellas impact basin in the Southern Hemisphere [lower right]."
Malin Space Systems has an animated view of the Mars 2001 opposition using images from the Mars Global Surveyor at Simulated Earth-based Views.
How does Earth look from Mars?
The image at right is an actual Martian sunset from the Mars Pathfinder mission with an added dot to represent how Earth might look as it approaches Mars opposition. The brownish gray sky is what would be seen by an observer on Mars in this true color mosaic taken on Sol 24 at approximately 4 p.m.. The Twin Peaks can be seen on the horizon. The sky near the sun is a pale blue color. (NASA/JPL Photo)
If you had a telescope on Mars could you see Earth? According to a NASA news release, the camera aboard Mars Global Surveyor (MGS) photographed Earth, the Moon and Jupiter in the evening sky of Mars, at 9 a.m. EDT, May 8, 2003.
"We've spent the last six-and-a-half years staring at Mars right in front of us", says Michael Malin, president and chief scientist of Malin Space Science Systems (MSSS), of San Diego, who operates the camera aboard MGS. "Taking this picture allowed us to look up from the work of exploring Mars ... and gain a new perspective on the neighborhood, one in which we can see our own planet as one among many."
"The image of Earth shows our home as a planetary disk, in a 'half-Earth' phase. The bright area at the top of the image of Earth is cloud cover over central and eastern North America. Below that, a darker area includes Central America and the Gulf of Mexico. Another bright feature is caused by clouds over South America.
"The Mars Global Surveyor Mission, one of the most successful missions to Mars ever undertaken, has been orbiting the red planet since September 1997. The mission has examined the entire martian surface and provided a wealth of information, including some stunning high-resolution imagery, about the planet's atmosphere and interior." (NASA/MSSS images and text.)
Retrograde Motion of Mars
If you plot the motion of Mars against the background stars of the night sky it will seem to move east, stop, move west (retrograde), stop, and finally begin moving east again. This is called retrograde motion. In 2003 it followed the path shown in this diagram. The planet moves in its elliptical orbit just as the rest of the planets but our view from Earth causes this illusion of the planet stopping. As the Earth catches up with Mars the planet seems to stop and go backwards just as you view another car that you overtake and pass on the highway. The loop is because the two orbits are not in exactly the same plane. All of the outer planets have some degree of retrograde motion relative to Earth.
It was this weird motion of Mars, Jupiter and Saturn that was hardest for early astronomers to explain. It was only after Copernicus, Keppler, Newton, Gallileo, and others discovered the various laws relating to motion and gravity that the mystery was solved. See the Basic Astronomy Facts page for a short history.
Who was Mars?
To the Norsemen, Mars was a one-handed god of war called, Tiu (TEE oo). Tuesday honors the god of war called Mars by the Romans and Ares (ER eez) by the Greeks. "All's fair in love and war" may be a reference to his affair with Venus. The Romans considered iron sacred to Mars and often had amulets made from the metal to protect them in battle.
Sometimes, Mars was related to agriculture and has his own spring month named after him, March. Spring was also the time the Roman legions began their conquests and, you guessed it, got their marching orders. Look at the Planet Myths and Lore pages for more mythology.
Field Trip to Mars
This virtual field trip is a self-guided excursion to view various sites located on or near the central plateau of Washington that correlate to features found on Mars. Click image or here to go to Field Trip to Mars.
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Here are some basic terms used for describing orbits and oppositions. Find more astronomical terms in the Glossary.
- The farthest point from the Sun of any object orbiting the Sun. Sun Facts
- The farthest point from Earth of any object orbiting Earth. The word apoapsis is used for objects orbiting other planets.
- Astronomical Unit
- The average distance between Earth and the Sun, 1.5 x 108 km.
- The position of two celestial objects when they are 0° apart as viewed from east to west on Earth. When the Sun is one of the objects the other is between it and Earth so is usually not visible.
- A pattern of stars usually named after animals or people in stories. Now used to designate an area in the celestial sphere.
- The path the Sun seems to follow in the sky. Also, Plane of the Ecliptic
- A partial or complete temporary hiding of one celestial object by another such as a planet moving in front of a star as seen from Earth.
- The position of two celestial objects when they are 180° apart as viewed from east to west on Earth. When the Sun is one of the objects the other is directly opposite it in the sky and can be seen all night.
- The path an object takes as it moves around another object.
- The closest point to Earth of any object orbiting Earth. The word periapsis is used for objects orbiting other planets.
- The closest point to the Sun of any object orbiting the Sun. Sun Facts
- An object spinning about its center.
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