August 18, 2019

Review: 2001: A Space Odyssey

This week, we here at Astroguyz are taking a look at a science fiction cinematic oldie but goodie. Stanley Kubrick’s 2001: A Space Odyssey makes the top of nearly every science geek’s short list of movies that bother to get the science right. And like its sequel, 2010, its just plain fun to look back now that those years have come and gone and see how well reality has held up.

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AstroEvent: Exploring Clavius.

This week, as the Moon moves past 1st Quarter on the 23rd toward Full on the 30th is a good time to explore the lunar environs. Specifically, I’d like to turn your attention towards Clavius crater, a prominent feature in the southern lunar highlands. One of the largest impact craters on the Moon at 152.2 miles across, it’s large enough to actually see the lunar curvature in its structure, and houses many smaller craters within its walls. It is visible starting at 9-10 days after New Moon, and presents a slightly different face each lunation. In fact, Clavius is one of the few craters that may be discerned by keen eyed viewers with the naked eye. In a small telescope, the relatively ancient structure of Clavius contrasts well with the nearby splashiness of young Tycho. Are these ancient, broad floored craters the result of impacts, or do they suggest early volcanic activity? Most of the rocks returned by Apollo astronauts were igneous and basaltic by nature, suggesting the young Moon once had a molten crust.

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Astro-Challenge: Spotting Two-Faced Iapetus.

As the majestic planet Saturn approaches opposition on March 21st, I’d like to turn your telescopic attention to one of the most bizarre moons in the solar system; Iapetus. It was way back when in the 17th century that Italian astronomer Giovanni Cassini noted that he could only see Iapetus when it was to the west of the ringed planet, but never to the east. He correctly deduced that Iapetus must not only be tidally locked, that is, holding one face towards Saturn, but must be correspondingly dark on one hemisphere and brighter on the other. In fact, Iapetus is known to vary from magnitude +10 to magnitude +12 over its 79 day orbit, a variation of 6 times in terms of brightness. the Cassini space probe has confirmed the duality of Iapetus, showing us a dark leading hemisphere with an albedo of 5% (think fresh asphalt) and a trailing hemisphere with an albedo of about 50% (think dirty snow). The third largest of the Saturnian moons, Iapetus is a “walnut shaped” world, with a large ridge running the equator of this twisted moon. Discovered by Cassini on New Year’s Eve 2004, no satisfactory explanation for the ridge is known, but the little world must have had a tumultuous history.

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