APOD - 2/21/09 = Comet Lulin

[smita]

Comet Lulin will be closest to earth on 2/24/09.
Would it be possible to see it with naked eye. If so, where should I look?

Thanks much. Pardon me, I am a newbie.

[neufer]

Comet Lulin will be closest to earth on 2/24/09.
Would it be possible to see it with naked eye. If so, where should I look?

Thanks much. Pardon me, I am a newbie.

Hi smita,

Get away from city lights and use binoculars:

http://www.skyandtelescope.com/observing/ataglance

[smita]

Thanks Art for the info. Will try it.

[orin stepanek]

http://apod.nasa.gov/apod/ap090221.html

"In fact, astronomers estimate Lulin was releasing about 800 gallons of water each second, enough to fill an Olympic-size swimming pool in less than 15 minutes."

That's a lot of water! I would think that the nucleus of the comet would have to be quite large to evaporate that much ice. I wonder does all that water get lost in space or remain in Lulin's atmosphere where it is precipitated back to the comet when it condenses?

Orin

[aristarchusinexile]

And where does all this water come from?

Thumbnail image of picture found for this day. APOD: November 29, 1999 - Arcs and Jets in Herbig Haro 34. Explanation: Some features of HH-34 are understood -- some are not. At the core of Herbig-Haro 34 lies a seemingly typical young star. This star, though, somehow ejects energetic "bullets" of high-energy particles, appearing as red streaks toward the lower right of the this image. Astronomers speculate that a burst of these particles might rebound when gas from a disk surrounding the star momentarily collapses onto the star. Visible near the end of each light-year long jet is a glowing cap. HH-34 lies about 1500 light-years away in the Orion Nebula star-forming region. The cause of the large arc of gas on the upper left known as the waterfall remains unexplained."

Globes of water being shot into space.

[Chris Peterson]

"In fact, astronomers estimate Lulin was releasing about 800 gallons of water each second, enough to fill an Olympic-size swimming pool in less than 15 minutes."

That's a lot of water! I would think that the nucleus of the comet would have to be quite large to evaporate that much ice. I wonder does all that water get lost in space or remain in Lulin's atmosphere where it is precipitated back to the comet when it condenses?

I haven't seen an estimate of the size of the nucleus (that's pretty hard to figure out, especially for an active comet), but 1km or more would by pretty typical. And that's a lot of Olympic sized pools!

A comet has nowhere near enough mass to attract anything that is ejected from its surface. All the gas will simply dissipate, and all the dust will end up generally along the orbital path, and will also dissipate over years. If the comet was periodic that dust might produce a meteor stream, but this comet is just making one pass through the inner system, and will never return.

[neufer]

http://apod.nasa.gov/apod/ap090221.html

"In fact, astronomers estimate Lulin was releasing about 800 gallons of water each second,
enough to fill an Olympic-size swimming pool in less than 15 minutes."

That's a lot of water! I would think that the nucleus of the comet would have to be quite large to evaporate that much ice. I wonder does all that water get lost in space or remain in Lulin's atmosphere where it is precipitated back to the comet when it condenses?

Anything that you can see with binoculars or even a telescope
is many radii away from the nucleus and won't be coming back.

Code: Select all

Average discharge in cubic meters/second

Amazon 	219,000
Danube 	__6,500
Lulin     ______3

800 gallons/sec ~ 0.1 cubic kilometers per year

A typical comet nucleus is ~ 1000 cubic kilometers.

[Chris Peterson]

And where does all this water come from?

Water is a simple molecule, formed from two abundant elements. It is naturally created in large quantities in regions of protostellar discs. Most of that water is still present in millions of trans-Neptunian bodies- some of which occasionally get knocked into the inner Solar System as comets.