APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep 03)

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APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep 03)

Post by APOD Robot » Sat Sep 03, 2011 4:12 am

Image Comet Garradd Passes Ten Thousand Stars

Explanation: Comet Garradd continues to brighten as it drifts across the northern sky. Last week the comet, visible with binoculars and discernable by its green coma, passed nearly in front of globular cluster M71. M71 was once thought to be an open cluster, but is now known to be an older globular cluster containing over 10,000 stars. The photogenic duo was captured with a standard digital camera in a 10-minute, wide-angle exposure toward the northern constellation of the Arrow (Sagitta). The stars Sham (Alpha Sagittae), Beta Sagittae, Gamma Sagittae, and the double star Delta Sagitta are all visible in a diagonal band running down from the upper left. Comet C/2009 P1 (Garradd), will remain visible in northern skies for months and will reach its closest approach to the Sun in December.

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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by bystander » Sat Sep 03, 2011 11:27 pm

"discernable" vs. "discernible" split to here.

For more images from Comet C/2009 P1 Garradd, see here.
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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by NoelC » Sat Sep 03, 2011 11:45 pm

Funny thing: Comets used to be all the rage. Consider that they're the reason for the Messier catalog. Now hardly anyone wants to talk about them at all, assuming they're not headed for a collision with Earth. Instead, everyone wants to talk about stuff that's 50 billion light-years distant, or can't be seen (but we know it's there) like dark matter and black holes.

Well I think the image is very pretty. I wish I could see stars like that from here, but there's just too much light pollution (not to mention swirly storms).

Regarding the image processing, I might have worked to differentiate the brighter stars from the dimmer ones a hair more, but that's just personal preference.

That little blob of green is beautiful up there where it's so rare.

-Noel

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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by neufer » Sun Sep 04, 2011 2:44 am

NoelC wrote:
Funny thing: Comets used to be all the rage. Consider that they're the reason for the Messier catalog. Now hardly anyone wants to talk about them at all, assuming they're not headed for a collision with Earth. Instead, everyone wants to talk about stuff that's 50 billion light-years distant, or can't be seen (but we know it's there) like dark matter and black holes.
Comets have been recorded for 2500 years and (other than eclipses, meteor showers & fireball/bolides)
they were the only exciting astronomical events for most of that time period.

There have already been 8 flyby spacecraft missions to 5 comets including an impact probe of Temple 1.

In 2014 Rosetta is scheduled to orbit and soft land a probe onto Churyumov–Gerasimenko.

Comets are still the rage but people no longer have the patience to appreciate them.
Last edited by neufer on Sun Sep 04, 2011 11:20 am, edited 1 time in total.
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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by Chris Peterson » Sun Sep 04, 2011 4:42 am

NoelC wrote:Funny thing: Comets used to be all the rage. Consider that they're the reason for the Messier catalog. Now hardly anyone wants to talk about them at all, assuming they're not headed for a collision with Earth. Instead, everyone wants to talk about stuff that's 50 billion light-years distant, or can't be seen (but we know it's there) like dark matter and black holes.
I'm not sure where you get that idea. I study meteoritics professionally, and I can assure you that there is a solid body of researchers looking at comets and asteroids, and there have been a number of missions to both. Comets are a hot area of research.
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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by Ann » Sun Sep 04, 2011 7:36 am

Comets are beautiful, and this APOD is beautiful.

The comet is now in the small constellation Sagitta, the Arrow, which is an interesting constellation. It is in the middle of the dust lane of the Milky Way, and you can expect interesting things to go on somewhere inside it. Things do happen, too, but generally "deep in the dust" of Sagitta and not on the "surface" of it.

All the bright stars of Sagitta, Alpha, Beta, Gamma and Delta are massive stars at respectable distances of 260 to 600 light-years, and they all shine between 200 and over 900 times the luminosity of the Sun. No puny little "Siriuses" here, which "only" emits 23 solar luminosities from a distance of barely 9 light-years!

Comet Garradd looks as if it has passed right over the face of M71, because its tail seem to point right at the globular. (But of course, a comet's tail does not so much point in the opposite direction of the comet's movement as it points in the opposite direction of the Sun.)

(By the way, what a pair: the globular cluster is about 12,000 light years away and the comet can't be more than, at most, a few light hours away. A light-half hour seems more probable to me.)

Note a line of stars that seems to curve away from the comet at lower right. The brightest of these stars is majestic O type star 9 Sagittae, which is so far away that Hipparcos couldn't measure a parallax for it. To me 9 Sagittae is the symbol of the amazing current goings-on in this deceptively quiet constellation, while the globular cluster is a reminder of glorious star formation events in the past. And the comet is a reminder of the liveliness of our own solar system, which is still alive and kicking after four and a half billion years. Yet like the constellation Sagitta, our solar system looks quiet and orderly, too, and in our case the reassuring quietness is no deception.

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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by Ann » Sun Sep 04, 2011 8:25 am

Got to add something. Constellation Sagitta is close to constellation Vulpecula, which is famous for its delightful asterism, the Coathanger. And guess what, Comet Garradd is right on its way to the Coathanger! :D
Image
Photo: Rolando Ligustri


Maybe Owlice has already posted this image. If so, I should probably not post it here. But it's fun, isn't it, that Comet Garradd gets to visit one famous astronomical object after another! :D





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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by neufer » Sun Sep 04, 2011 11:44 am

Click to play embedded YouTube video.
α Sge: also known as Sham

bright yellow giant star of spectral class G1 II
(with 4.37m) at a distance of 610 light-years.
Ann wrote:
All the bright stars of Sagitta, Alpha, Beta, Gamma and Delta are massive stars at respectable distances of 260 to 600 light-years, and they all shine between 200 and over 900 times the luminosity of the Sun. No puny little "Siriuses" here, which "only" emits 23 solar luminosities from a distance of barely 9 light-years!
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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by Beyond » Sun Sep 04, 2011 4:34 pm

The Original Wooley Bully.
woolly-mammoth1.jpg
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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by BMAONE23 » Sun Sep 04, 2011 6:16 pm


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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by masterminds » Mon Jun 25, 2012 11:08 am

When I face the problems of everyday life, I look at one of the APOD pictures, such as this one, to bring things into scale. We often think the world ends here at the Earth. The truth is, we are extremely insignificant in the grand scheme of things.

Image
Last edited by owlice on Mon Jun 25, 2012 11:27 am, edited 1 time in total.
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Re: APOD: Comet Garradd Passes Ten Thousand Stars (2011 Sep

Post by neufer » Mon Jun 25, 2012 12:33 pm

masterminds wrote:
When I face the problems of everyday life, I look at one of the APOD pictures, such as this one, to bring things into scale. We often think the world ends here at the Earth. The truth is, we are extremely insignificant in the grand scheme of things.
Speak for yourself, masterminds.
Art Neuendorffer