July 20, 2019

29.9.9: Can you Spot the Cave in Copernicus?

I’ve got a unique challenge for you, as you brush up on your lunar geography in anticipation for next weeks’ LCROSS impact. Next time you’re viewing the waxing gibbous Moon with your friends, amaze them (or make them think your totally crazy) by issuing the off-handed remark; “Did you know that there is a ‘cave’ in the crater Copernicus? The “cave” in question is, of course, an optical illusion. Its interesting to note, however, that in the pre-Apollo era, would-be Selenographers were faced with a lunar landscape that was much less straight forward. This first came to our attention while reading a February 2003 article in Sky & Telescope written by Steven O’Meara. The cave itself rests on the northern inner lip of the crater and is elusive unless caught at the precise sun-angle of 10.7 degrees above the local lunar horizon. This generally occurs around 10-12 days of age, and I encourage you to take a look early this week. [Read more...]

LCROSS target crater announced.

Scientists at NASA have announced the candidate target crater for the LCROSS impactor on October 9th; Cabeus A, a 11km wide polar crater thought to contain the ever- elusive water ice. The Centaur upper stage will slam into the carter floor at 7:30 AM EDT, at which time the Moon will be waning gibbous, and about 70% illuminated, and favoring viewers in the Americas (including Astroguyz HQ!). Contrary to earlier fears, LCROSS has enough fuel to make final maneuvers for impact. Both Keck observatories and LCROSS’s twin, the Lunar Reconnaissance Orbiter, as well as a multitude of eager amateur observers will be on hand to witness this rare event!

Astro Event of the Week; November 17th-23rd: The Leonids.

Hang on for one the biggest, baddest meteor showers of all; the Leonids are scheduled to peak this year on the morning of November 17th. radiating from the asterism known as “the Sickle” in the constellation Leo the Lion,  the Leonids are debris left over from the comet Tempel-Tuttle. Most years, the Leonids are feeble, only generating 10 meteors per hour, but every 33 years or so, (most recently the 1998-1999 seasons) this shower becomes a true meteor storm. Will the Leonids produce this year? The only sure way to tell is to keep an eye on the sky the early morning hours this week! The waning gibbous Moon may thwart some of the fainter meteors, but check it out and note what you see, none the less!

This weeks’ Astro-word of the week is Bolide. A meteor becomes a bolide (think “blow up”) when it explodes in our atmosphere… and impressive sight, indeed!