Asteroids

APOD – 11/12/12Explanation: Which feature takes your breath away first in this encompassing

panorama of land and sky? The competition is strong with a waterfall,

meteor, starfield, and even a moonbow all vying for attention. It is interesting to first

note, though, what can't be seen -- a rising moon on the other side of the camera. The

bright moon not only illuminated this beautiful landscape in Queensland,

Australia last June, but also created the beautiful moonbow seen in front of

Wallaman Falls. Just above the ridge in the above image is the horizontal streak of an airplane. Toward the top of the frame is the

downward streak of a bright meteor, a small pebble from across our Solar System

that lit up as it entered the Earth's atmosphere. Well behind the meteor are numerous bright stars and nebula seen

toward the center of our Galaxy. Finally, far in the background, is the band of our Milky Way Galaxy, running diagonally from the

lower left to the upper right in the image but also circling the entire sky.

• Explanation: Some people are so inspired by solar eclipses that they quilt. Pictured above is a resulting textile from one such inspiration. The 38x38 inch quilt offers impressions of a total annular eclipse, when the Moon is too far from the Earth to cover the entire Sun, witnessed in Spain in October of 2005. Today, however, a full total solar eclipse will occur, although it will only be visible to eclipse chasers and those who live in a thin swath of Australia. For a few minutes, those near the center of the eclipse path will see the entire Sun blocked by the Moon, causing the day to become unusually dark. Just before -- and just after -- totality occurs, sunlight may stream between mountains on the Moon's edge creating a diamond ring effect. The next total eclipse of the Sun will occur in November 2013.

APOD November 13, 2012

Three different types of asteroids: 

• C- type: Carbonaceous (stony and darker than coal)

• S- type: Silicaceous (bright, stony bodies which contain metal)

• M-type: Metallic (exposed metallic cores of much larger bodies)

Lutetia (C – type)

M-type

Eros (S-type) – closest to Earth

Ceres – largest of the asteroids found in 1801, now considered a

dwarf planet (C-type)

950 km wide, it resides in the Main Belt of Asteroids

Asteroid Classes

• Asteroid Belt (between Mars and Jupiter)

• Trojan Asteroids (60o before or 60o after Jupiter – in the same orbit)

• Apollo Asteroids (cross the orbit of Earth)

• Amor Asteroids (cross the orbit of Mars)

Meteors, Meteoroids, Meteorites

• Meteor – bright streak in the sky (“shooting star”) • Meteoroid – chunk of debris before it hits the

Earth’s surface• Meteorite – the part of the meteoroid that

reaches the Earth’s surface

• Crater – bowl shaped depression resulting from the collision of debris with a planet’s surface

Craters on the Moon

Craters on Mercury

Craters on Earth

Barrington Crater• Arizona

• Measuring 1.2 km across and 175 m deep

• Formed about 50,000 years ago