This artist's concept of asteroid 3 June shows the "bite" taken out of the asteroid by an impact. (David A. Aguilar, Harvard-Smithsonian Center for Astrophysics)
Images of asteroid 3 Juno taken with the 100-inch Hooker telescope at Mt. Wilson Observatory show what appears to be a 60-mile-wide crater. The crater is visible as a darkened area in the lower left quadrant in the 833 nm and 934 nm images. The material excavated by the collision that produced the crater "bite" has low reflectance, especially at the wavelength of 934 nm. An adaptive optics system provided a remarkably clear view of Juno's surface by reducing interference from the Earth's atmosphere. (Sallie Baliunas et al.)
From the the NASA JPL News Release...
Juno, one of the first asteroids discovered, is thought to be the parent of many of the meteorites that rain on Earth. The asteroid is composed mostly of hardy silicate rock, which is tough enough that fragments broken off by collisions can often survive a trip through Earth's atmosphere.
Though pockmarked by bang-ups with other asteroids, Juno is large; in fact, it is the tenth largest asteroid. It measures about 234 kilometers (145 miles) in diameter, or about one-fifteenth the diameter of the moon.
The asteroid, which orbits the sun on a track between Mars and Jupiter, will be at its brightest on Sept. 21, when it is zooming around the sun at about 22 kilometers per second (49,000 miles per hour). At that time, its apparent magnitude will be 7.6, which is about two-and- a-half times brighter than normal. The extra brightness will come from its position in a direct line with the sun and its proximity to Earth. (The asteroid will still be about 180 million kilometers [112 million miles] away, so there is no danger it will fall towards Earth.)
Skywatchers with telescopes can probably see Juno from now until the end of the year, but it is most visible to binoculars in late September. On or before Sept. 21, look for Juno near midnight a few degrees east of the brighter glow of Uranus and in the constellation Pisces. It will look like a gray dot in the sky, and each night at the end of September, it will appear slightly more southwest of its location the night before. By Sept. 25, it will be closer to the constellation Aquarius and best seen before midnight.
Link: NASA JPL Article
Link: Wikipedia: 3_Juno
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