Spring dates and updates…

Sorry for the hiatus folks, but never fear, the science is here. Here’s a run down of some cool things that have going on in the space world recently :

  • Everybody’s favorite exoplanet-searching space telescope, Kepler, has found two planets in the same orbit around a single star. There’s nothing in gravitational theory that says that two planets can’t share a single orbit, in fact Jupiter has clumps of asteroids (the Trojans– as explained in Alas, poor Pluto…) that share its orbit, but this marks the first time we’ve ever actually seen two planets share an orbit anywhere in the universe. But then again, we’ve really only recently begun seeing planets outside our solar system at all, so I guess that’s not so surprising. But in any case, it’s nice to now have observational proof that it can happen. The really cool thing about this discovery is that it helps strengthen one of the leading hypotheses for the formation of the Moon. It’s pretty commonly accepted that the Moon was formed roughly 4.5 billion years ago by an impact with an object about the size of Mars (roughly half the size of Earth). Some scientists now believe that that Mars-sized object might have actually shared an orbit with Earth

An artist’s depiction of the two gas giant planets sharing an orbit. Credit: NASA/Ames/JPL-Caltech

  • NASA’s Sun-staring STEREO mission has successfully imaged the entire Sun for the first time ever. STEREO consists of two satellites launched from Earth in opposite directions, one ahead of Earth in its orbit and one behind, back in 2006. Since then, the two satellites have been racing away from each other to the far side of the Sun. Having two satellites allows scientists to observe the Sun in 3D, an ability all other solar observatories are lacking. Not only does STEREO create some pretty amazing press releases (lots of “oooh ahhh” pictures and videos), but it has really helped the advancement of heliophysics (the study of the Sun). At the end of February they reached opposite sides of the Sun and for the first time allowed scientists to observe the entire Sun at once. You can check out the full movie of the 360 Sun here, but in the mean time check out this awesome image:

The roughly 6000 K degree surface or photosphere of the Sun. Credit: NASA

  • NASA’s MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) satellite finally entered orbit around Mercury on March 18 and has already begun sending back some amazing images of the smallest planet’s crater-ridden surface. Mercury is an extremely interesting planet. For starters, because its rotational period (aka the Mercurian day- or how long it takes to rotate on its axis) is comparable to its orbital period (aka the Mercury year, how long it takes to orbit the Sun), basically one side of Mercury is exposed to constant sunlight for months while the other side is left in total darkness. This leads to the largest temperature difference we know of in the solar system: the dayside can reach temperatures over 600˚F while the dark side can drop below -100˚F. (Surprisingly although it’s the closest to the Sun, Mercury is not the hottest place in the solar system. That honor actually goes to Venus, whose dense cloud cover and volcanic activity have led to a runaway greenhouse effect that has driven the planet’s temperature well over 900˚F.) Mercury is also interesting because it has an unusually large core. We’re pretty sure that all of the rocky inner planets- Mercury, Venus, Earth, Mars- have sizable metallic cores. Earth’s, for example, is made primarily of iron and nickel and is about a third of Earth’s radius (roughly 16% of the planet’s volume). Mercury’s core on the other hand is huge, taking up roughly half (42%) of the planet’s volume. This oddity has lead some scientists to hypothesize that the tiniest world may have once been much larger, but had its outer layers knocked off by some cataclysmic impact. That idea isn’t as far fetched as one might think; there are several phenomena in the solar system which scientists attribute to large collisions. For example, the Moon’s formation (see the first bullet), the fact that Venus is the only planet in the solar system that rotates around its axis in the opposite direction that it orbits (all the other planets orbit the Sun counterclockwise and rotate counterclockwise, Venus is counterclockwise and clockwise), and the fact that Uranus is basically on its side (its angle with respect to the disk of the rest of the solar system is 97˚!

    Mercury’s suface is similar to that of the Moon– covered in craters– since neither body has an atmosphere to protect it from impacts. Credit: NASA

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