comets

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Comet PANSTARRS: The Show is not Over Yet

While Comet C/2011 L4 (PANSTARRS) is fading to barely naked-eye and binocular visibility (the comet has lost a full magnitude approximately every week since perihelion on March 9), astrophotographers are still able to track down the comet as it moves away from the Sun. This deep color exposure by Chris Schur in Arizona is still able to show surprising detail and Chris said that he was “surprised how beautifully colored the stars are in this part of the Milky Way.” Chris’s shot is a 25 minute exposure, and is an LRGB (Luminance, Red, Green and Blue — is a photographic technique used in amateur astronomy for producing good quality color photographs by combining a high-quality black-and-white image with a color image).

See some more recent PANSTARRS images from around the world, below, plus an awesome new timelapse from TWAN (The World At Night) photographer P-M Hedén:

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Comets have two tails.

There are two types of comet tails: dust and gas ion.

A dust tail contains small, solid particles that are about the same size found in cigarette smoke. This tail forms because sunlight pushes on these small particles, gently shoving them away from the comet’s nucleus. Because the pressure from sunlight is relatively weak, the dust particles end up forming a diffuse, curved tail.

A gas ion tail forms when ultraviolet sunlight rips one or more electrons from gas atoms in the coma, making them into ions (a process called ionization). The solar wind then carries these ions straight outward away from the Sun. The resulting tail is straighter and narrower. Both types of tails may extend millions of kilometers into space. As a comet heads away from the Sun, its tail dissipates, its coma disappears, and the matter contained in its nucleus freezes into a rock-like material.

Comets don’t like the sun.

Comets lose a lot of mass when they go by the Sun. A lot: some shed hundreds of tons of material per second. That’s actually a small fraction of the mass of a comet, but given time, and lots of solar passes, it adds up. Every comet we see is slowly dissolving in space. Eventually even the mighty Comet Halley will be gone, broken down into a swarm of rocks, gravel, and dust once its gas is gone.

“It’s life, Jim, but not as we know it.”

Rosetta finds key building blocks of life in comet dust:

The amino acid glycine, one of the key building blocks of life as we know it, has been found in the “fuzzy atmosphere” of comet 67P Churyumov-Gerasimenko, the European Space Agency announced today. The findings mean it is likely the glycine was carried through space on the surface of the comet.

But this is the real mind-blower:

The confirmation supports the idea that amino acids are common around star-forming regions of the universe and were likely delivered to Earth by a comet or other celestial object.

We are truly stardust.