Image taken by the Mars Global Surveyor of a (building sized) monolith found on Phobos, a moon of the planet Mars
A fantasy on exploration of the solar system
On Mercury we’ve lived through a Sun rise
We’ve trudged through the sand dunes of Mars
We’ve stumbled through firestorms on Venus
Strange landscapes here under the stars
We’ve dived into oceans of giants
Flown inside their shepherded rings
From Jupiter out to far Neptune
On moons we’ve seen wonderful things
We’ve found an abundance of life forms
Each world has a number for sure
Intelligence, sentience, prospers
Some clearly defined, some obscure
It seems there were older explorers
Who left traces that we have found
Their monuments standing like statues
And habitats built underground
We’ve seen man’s intentions to follow
To seek out his fortune in space
His self-centredness might soon be tested
If he meets the ones of our race
Notes:
Interesting and detailed descriptions of Solar System objects can be found at nineplanets.org. A few details I found especially fascinating are reproduced below, with thanks.
Mercury
Mercury has no moons.
This fact and the high eccentricity of Mercury’s orbit would produce very strange effects for an observer on Mercury’s surface. At some longitudes, the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point, the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while, the stars would be moving three times faster across the sky. Observers at other points on Mercury’s surface would see different but equally bizarre motions.
Venus
Venus has no moons.
Venus’ rotation is somewhat unusual in that it is both very slow (243 Earth days per Venus day, slightly longer than Venus’ year) and retrograde (clockwise – Jan). In addition, the periods of Venus’ rotation and of its orbit are synchronized such that it always presents the same face toward Earth when the two planets are at their closest approach. Whether this is a resonance effect (due to gravitational interaction – Jan) or merely a coincidence is not known.
Mars
Mars has two moons.
Mars has some of the most highly varied and interesting terrain of any of the terrestrial planets, some of it quite spectacular:
Olympus Mons: the largest mountain in the Solar System rising 24 km (78,000 ft.) above the surrounding plain. Its base is more than 500 km in diameter and is rimmed by a cliff 6 km (20,000 ft) high.
Tharsis: a huge bulge on the Martian surface that is about 4000 km across and 10 km high.
Valles Marineris: a system of canyons 4000 km long and from 2 to 7 km deep (top of page);
Hellas Planitia: an impact crater in the southern hemisphere over 6 km deep and 2000 km in diameter.
Jupiter
Jupiter has 63 known moons (as of Feb 2004).
The Great Red Spot (GRS) has been seen by Earthly observers for more than 300 years (its discovery is usually attributed to Cassini, or Robert Hooke in the 17th century). The GRS is an oval about 12,000 by 25,000 km, big enough to hold two Earths. Other smaller but similar spots have been known for decades. Infrared observations and the direction of its rotation indicate that the GRS is a high-pressure region whose cloud tops are significantly higher and colder than the surrounding regions. Similar structures have been seen on Saturn and Neptune. It is not known how such structures can persist for so long.
Saturn
Saturn has 53 named moons (as of spring 2010).
Saturn’s rings are extraordinarily thin: though they’re 250,000 km or more in diameter, they’re less than one kilometre thick. Despite their impressive appearance, there’s really very little material in the rings — if the rings were compressed into a single body it would be no more than 100 km across. The ring particles seem to be composed primarily of water ice, but they may also include rocky particles with icy coatings.
Some of the moons, the so-called “shepherding satellites” are clearly important in keeping the rings in place.
Uranus
Uranus has 27 named moons.
Most of the planets spin on an axis nearly perpendicular to the plane of the ecliptic (the Earth’s orbit – Jan) but Uranus’ axis is almost parallel to the ecliptic. At the time of Voyager 2’s passage, Uranus’ south pole was pointed almost directly at the Sun. This results in the odd fact that Uranus’ polar regions receive more energy input from the Sun than do its equatorial regions. Uranus is nevertheless hotter at its equator than at its poles. The mechanism underlying this is unknown.
Neptune
Neptune has 13 known moons.
Neptune’s blue colour is largely the result of absorption of red light by methane in the atmosphere but there is some additional as-yet-unidentified constituent, which gives the clouds their rich blue tint.
Neptune has rapid winds confined to bands of latitude and large storms or vortices. Neptune’s winds are the fastest in the solar system, reaching 2000 km/hour – mechanism unknown.
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