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

Jupiter and Venus meet over supper

Catch the crescent moon as it moves up and away from the western horizon in the next two days. During the same time, Venus glides slowly higher while Jupiter drops further westward. The two are in conjunction and only 1/2 degree apart Tuesday evening very low in the west-southwest about 15-20 minutes after sunset. Created with Stellarium

The Endeavour space shuttle and International Space Station (ISS) orbit the Earth together. Credit: NASA

The shuttle and space station will continue to delight morning sky watchers this coming week. Here are the times (CST) for viewing the Endeavour/ISS pair as they cross the dawn sky together this coming week. These should be accurate for N. Minn / NW Wisc. For times for your town, click HERE and enter your zip code.

* Tuesday Feb. 16 starting at 5:57 a.m. across the northern sky.

* Weds. Feb. 17 at 6:18 a.m. Brilliant pass across the north-northeast.

* Thurs. Feb. 18 at 6:41 a.m. Watch for a brilliant pass high in the south.

* Fri. Feb. 19 at 5:30 a.m. across the north.

* Sat. Feb. 20 at 5:52 a.m. high across the south. Brightest crossing of the week!

The photo at left is a little blurry but it's one of the best pictures we have of the 329-mile diameter asteroid 4 Vesta. In the computer model you can better see the enormous crater at its south pole. Credit: NASA/ESA

Did you get a chance yet to find asteroid 4 Vesta? On Saturday night, the sky was dark enough here I could just see it with my naked eye. To figure out what asteroids are made of astronomers use an instrument called a spectroscope that dissects light into very fine gradations of color. They point it at an object like Vesta and study the sunlight it reflects. Minerals absorb and reflect specific colors of light and imprint it with their individual chemical "signature". Scientists studying Vesta find the very same signatures in its light as they do in a group of igneous meteorites found here on Earth.

A slice of the eucrite meteorite NWA 3147 that's likely originated in a lava flow on the surface of Vesta. The rock is composed of small mineral crystals feldspar and pyroxene. Photo: Bob King

The meteorites fall into three categories: eucrites (YOU-crytes), formed in surface lava flows, diogenites (DYE-uh-JEN-ites), from magma that solidified deeper inside the asteroid and howardites, created by the mixing of the two through impact bombardment on the asteroid's surface.

This is the howardite NWA 3149. You can see it's made of broken pieces of other rocks that were cemented together by the heat and pressure of impact. Photo: Bob King

The match between these types and different areas of Vesta's surface is excellent. Amazing that these chips from an asteroid were delivered right into our laps. Astronomers suspect they got here through a huge impact on Vesta. Take a look at the photo above by the Hubble Space Telescope. The piece missing on the asteroid's bottom is a crater 270 miles in diameter and eight miles deep that was excavated by an asteroid impact long ago. It knocked off tons of material and created not only the vestoid family of asteroids but shot pieces across the solar system, some of which found new homes on our planet.

In 2011, NASA's Dawn spacecraft will orbit Vesta and explore it in great detail. Wow, that's just a year from now. To learn more about Vesta while you're passing the time, please click HERE.

Posted by: rking@duluthnews.com on 2/14/2010 at 11:21 PM | Comments (0) | Permalink | Edit

Tags: space station, astro bob, daily updates, life, moon, crescent, venus, jupiter, conjunction, vesta, meteorite, eucrite, howardite, diogenite, iss, endeavour