"Tenuous at best," was all he had to say
when pressed about the rest of it
(the world, that is)…
less seven comes to three
Them, you, us
thank the Heavens
for their elasticity,
as for those who live and die
-Andrew Bird, “Tenuousness”
It has been said that astrophysics differs from the study of physics in an earth-based laboratory because astrophysicists are unable to control the conditions in the cosmic environment. In the lab, earthly physicists are permitted to tinker and massage combinations of variables. With the help of specially designed instruments and an armada of gauges, cables, switches, and buttons, they are capable of arranging their environment in the “ideal” configuration for their investigations. The physics of the earth-bound scientist is, one might say, rife with “knobs.”
For astrophysicists, however, the world is somewhat different. They must formulate their conclusions not from controlled experiments where variables can be manipulated and removed, but merely from close scrutiny of the variables with which nature chooses to present them. Like a detective who must deduce the personality and station of a suspect by the mark of his boot, the astronomer determines the composition of a galaxy or the mass of a star wielding nothing more than the information contained in a few electromagnetic waves.
The planetary scientist, on the other hand, occupies a nebulous region somewhere between the world of the physicist and the realm of the astronomer. Fueled by advances in space flight and instrumentation, the “in situ” (Latin for “on site”) revolution in planetary science has sent satellite observatories to the far reaches of our Solar System, landed probes on Mars, Venus, and Titan, and even allowed us to interactively investigate the surface of Mars with mini-field-geologist Rovers. These in situ missions are equipped with many of the same instruments that are veterans of terrestrial experimental physics. Modern engineering, it seems, is bringing the lab to the space environment.
-Kassandra Wells, “Astronomy with Knobs”
Also, this is a very unsettling orientation from which to look at Mars. Perhaps they corrected for obliquity ~2 Gyr in the past?
The Waters of Mars
The above image shows a basic simulation of what Mars may have looked like two billion years ago. Note the ocean.
Evidence has come to light that Mar’s lowlands may have been covered in water. This idea has come about as samples of rock show an abundance of phyllosilicates (a type of mineral) when compared to rock samples from higher elevations. As phyllosilicates are usually found in salt water on Earth so the logical conclusion to make is that parts of Mars were once submerged by oceans. Before you go pack your time machine for a visit to the ancient beaches of Mars it should be noted that this ocean would have been frigid and rimmed by glaciers. When taking a look at the coast line the geological evidence supports this, often showing signs of glacial wear and tear along with deposits of rocks known as moraines.
Guys, the Moon. Seriously. I’ve been working with a lot of beautiful LROC (Lunar Reconnaisance Orbiter Camera) photos, but, for obvious reasons, I can’t post those until they’re published. For now, enjoy this reblogged photo, released by the LROC team.
A small amount of impact melt pooled and froze on the floor of this Copernican impact crater, and is 90 x 70 m in size. LROC NAC M111972680LE, image width is 750 m. Credit: NASA/GSFC/Arizona State University. (via LROC)