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).
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
At 19, I read a sentence that re-terraformed my head: “The level of matter in the universe has been constant since the Big Bang.”
In all the aeons we have lost nothing, we have gained nothing - not a speck, not a grain, not a breath. The universe is simply a sealed, twisting kaleidoscope that has reordered itself a trillion trillion trillion times over.
Each baby, then, is a unique collision - a cocktail, a remix - of all that has come before: made from molecules of Napoleon and stardust and comets and whale tooth; colloidal mercury and Cleopatra’s breath: and with the same darkness that is between the stars between, and inside, our own atoms.
When you know this, you suddenly see the crowded top deck of the bus, in the rain, as a miracle: this collection of people is by way of a starburst constellation. Families are bright, irregular-shaped nebulae. Finding a person you love is like galaxies colliding. We are all peculiar, unrepeatable, perambulating micro-universes - we have never been before and we will never be again. Oh God, the sheer exuberant, unlikely fact of our existences. The honour of being alive. They will never be able to make you again. Don’t you dare waste a second of it thinking something better will happen when it ends. Don’t you dare.