All About Mars
- The fourth planet from the Sun
- The second nearest planet to the Earth and probably the first planet that will be visited by humans
- It’s orbit is equal to 687 Earth days
- It’s day is equivalent to 24hrs 37mins and 22.6 seconds, so there are 668 Martian days in a Martian Year
Mars – The Planet:
- Mars can be seen in great detail even with small telescopes
- Its polar ice caps are easily visible
- There are many bright areas on the red planet that are in fact deep basins on the planet’s surface
- There are also dark areas on the planet’s surface that were once thought to be seas, but when the atmospheric pressure was discovered to be too low for liquid water, they where then thought to be old sea beds filled with vegetation. However all this was disproved after the first fly-by mission by Mariner 4 in 1965. And two NASA rovers, Spirit and Opportunity, have since beamed back images of the Martian surface, which they explored.
- The highest known surface point on Mars is a huge volcano known as ‘Olympus Mons’. It stretches 24km high above the lava plains around it and it has a base measuring 600km
Mars – The Climate:
- Mars has an average surface temperature of about -23°C
- Its atmospheric content includes 95% carbon dioxide, 3% nitrogen and 1.6% argon
- Mars is not as dense or as large as Earth and can only sustain a thin, transparent atmosphere. However, some clouds can be seen and from time to time the occasional dust storm can completely cover the Martian surface
Mars – Factfile
- Mars has two moons – Phobos and Deimos, both discovered in 1877 by Asaph Hall. These two moons are shaped irregularly and are probably asteroids that were caught by Mars’ gravitational pull a long time ago. Neither is large enough to become spherical, and both have synchronous rotations enabling them to always keep the same face towards Mars.
- Phobos orbits at a distance of less than 6,000 km from the surface of Mars and, with a maximum diameter of 27 km, is larger than Deimos. It has been falling very slowly towards the planet at a rate of 10 km every century, and so will collide with Mars in forty million years.
- Deimos is even smaller than Phobos, and is only 15 kms wide. It, though, does have a stable orbit
Timeline to the discovery of Mars
- 1,500 BC – Egyptians refer to Mars as ‘Horus of the Hawk’, a god with the head of a hawk. They note its retrograde motion, when it moves backwards in its orbit relative to Earth
- 350 BC – Aristotle first proposes that Mars orbits at a further distance than the moon when he notes that the moon passes in front of Mars in his observations.
- 1609 – Galileo Galilei uses a telescope to become the first person to directly observe Mars, but is later vilified by the Vatican for asserting that the planets orbit the Sun and not earth.
- 1666 – Astronomer Giovanni Cassini calculates the length of a Martian day, notes the polar ice caps and even calculates its distance from Earth in his telescopic observations.
- 1840 – Astronomers Wilhelm Beer and Johann Heinrich Mädler study Mars through a 3.75-inch telescope and produce the first sketched Map of its surface.
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