Before we wrap up our appreciation of the full moon, can I add one more way? Last October 9, the LCROSS spacecraft and its companion rocket stage were crashed into the floor of the lunar crater Cabeus near the moon’s south pole. Earlier, scientists had picked up hints of water ice in this and other craters in the polar regions. The lunar poles are literally areas “where the sun don’t shine.” They likely acquired their ice from long-ago comet hits, and it’s been preserved in the shadows ever since. Steady temperatures of 280 below zero Fahrenheit are common in a number of polar craters – low enough to prevent water ice from vaporizing for at least a billion years.
By observing the resulting impact plume, scientists initially confirmed the presence of water ice. Fast forward to this week when NASA scientists announced that much more ice and vapor were seen in the plume than expected. How about 41 gallons?
Mission chief scientist Anthony Colaprete of the NASA Ames Research Center calculates there could be 1 billion gallons of water in Cabeus. Talk about an oasis in a lunar desert! The water is in the form of ice grains bound up with the lunar soil, but could be separated and used by future astronauts as drinking water. That’s not all that LCROSS kicked up. Scientists found methane, ammonia, hydrogen gas, carbon dioxide and carbon monoxide as well as relatively large amounts of light metals such as sodium, mercury and possibly even silver. That nasty ammonia and methane can be processed to make rocket fuel. All of these compounds and ices in the lunar soil indicate that the moon has a “water cycle” of sorts, where icy vapors from comet strikes in the distant past may have migrated to the poles where they condensed into ice and interacted with other compounds. “The diversity and abundance of volatiles in the plume suggest a variety of sources, like comets and asteroids, and an active water cycle within the lunar shadows,” says Colaprete. Direct your gaze to the southern edge of the moon tonight and think about the unexpected treasures there. You’ll find more information HERE and some cool videos HERE.
Although it looks like clouds for northern Minnesota this evening, if the weather’s fair by you, there are two interesting things going on tonight – one visible with the naked eye, the other in small telescopes. The Demon Star Algol in Perseus will undergo an eclipse by its larger, fainter companion. Mid-eclipse, when Algol is faintest, occurs at 11:10 p.m. Central time. This is ideal for watching Algol fade from near maximum brightness to minimum. If you’re out early, use the moon to help point you there. From nightfall until about 8:30 p.m. the star will appear its normal brightness. Look again around 10:30-11 p.m. and you’ll see it’s dimmed noticeably. For more information on Algol and its eclipses, check out this previous blog on the topic.
I’m going to hate to miss this next one – a simultaneous shadow transit of the moons Europa and Ganymede across the face of Jupiter. Between 8:40 and 10:04 p.m. Central time, the shadows cast by the two moons will appear as inky black dots on Jupiter’s cloud tops. If you could somehow float in a balloon within the shadow, you’d see an eclipse of the sun.
Europa’s shadow is a little larger than a pinpoint, while Ganymede, the largest of the Jupiter’s moons,Â looks more like a small dot. I’ve drawn the map for around 9:15 p.m when they’ll both be most easily visible at the same time. Ganymede itself is well removed to the left of Jupiter; Europa is in front of the planet until about 9:40, when it begins to move off and to the side of the planet. If you use high power, you can watch Europa – a tiny white speck – glide off the disk in real time. A wonderful sight!