Astro Bob A look at celestial happenings in the Northland and beyond Bob King View my profile Click here to view previous posts or additional resources

Luna is the Russian word for moon

The 2-day-old crescent with its lollipop of earthshine made a striking sight last night in the western sky. The crescent will be higher tonight and the earthshine nearly as pronounced. Details: 400mm lens at f/5.6, ISO 1600 and one-second exposure. Photo: Bob King

Wow, did it ever feel like spring last night. There's just something about a west breeze, 40-degree temperatures and the smile of a crescent moon at dusk that wraps you up and carries you straight out of winter. Who could resist that moon? I looked at it in the telescope and was blown away by the large chain of craters filled with inky shadow that lined the central section of the crescent. Stevenus-Snellius-Petavius-Vendelius-Langrenus. The cadence of the names is like a magic spell cast to charm our eyes in their direction. The craters range from 52 miles in diameter for Snellius to 110 for Petavius. Notice how oval they are. We see them from the side along the steeply curving edge of the moon which causes their outlines to become foreshortened. If you could hover directly over them, they'd be just as circular as the craters we see near the center of the moon.

Five craters in a row pock the lunar terminator (day-night border) on the moon last night. Stevinus and Snellius were still heavily shadowed at the time. Photo: Bob King

Petavius has a cluster of mountain peaks at its center which reach a mile and half high. In the photo above their tops are catching the first rays of early morning sun. Tonight the crescent will be thicker, and our featured craters will be out of the shadows and basking in sunlight. A small telescope will show them with ease. And don't pass up the opportunity to take in a little earthshine while you're at it. This "twice reflected" light originates from sunlight that reflects off planet Earth and then bounces back off the moon.

The tracks of the Russian moon rover Lunokhod 2 are plainly visible on the right side of the photo with the rover itself at top. The impressions were made 37 years ago during Lunokhod's exploration at LeMonnier crater. Credit: NASA

We've written about photos taken by the Lunar Reconnaissance Orbiter (LRO) of the Apollo lunar lander sites that show equipment and even the astronauts' footpaths on the moon's surface. NASA recently released a new photo taken by the LRO of the Russian Lunokhod 2 rover and its tracks near LeMonnier crater in the Sea of Serenity. Lunokhod 2, which means "moon walker", was launched on the Luna 21 spacecraft in January 8, 1973 and landed on the moon on the 15th. The rover was equipped with TV cameras that allowed controllers on Earth to navigate it across 23 miles of the moon's surface.This trek still stands as the long-distance record for robotic rovers on other worlds. For comparison, the Mars Spirit Rover has covered 4.8 miles and Opportunity 12.1 miles since landing in early 2004.

One of the Lunokhod rovers. The Russians spell it in Cyrillic but their word for moon is "luna". Credit: Petar M.

The primary mission of the Russian rovers was to take photos of the moon's surface, determine the physical and mechanical properties of the lunar soil called regolith, examine local magnetic fields and even study X-rays emanating from the sun. All the instruments were protected by a clamshell-like lid that when opened up exposed an inner surface lined with solar cells used to provide power. A radioactive source was used to keep the Lunokhod warm during the two-week-long lunar night when temperatures dropped to almost 250 below zero.

Americans generally don't give much thought to the Russian moon program but beginning in 1959 with Luna 1 the Russians were just as busy as we were sending satellites and landers to take pictures and study the lunar environment. The Luna 16, 20 and 24 unmanned sample return missions between 1970 and 1976 succeeded in bringing home a total of 320 grams of material from the moon drilled from the regolith of the Seas of Fertility and Crises. Next year the Russians will partner with the European Space Agency to send a lander to the Mars' moon Phobos. Their desire to explore the solar system parallels our own country's, but this time around without the anxiety-producing background of an arms race.

Posted by: rking@duluthnews.com on 3/18/2010 at 10:00 AM | Comments (0) | Permalink | Edit

Tags: daily updates, moon rover, astro bob, life, moon, crescent, craters, moon, russia, lunokhod