APOD: An Active Night over the Magellan... (2017 Feb 21)

Comments and questions about the APOD on the main view screen.
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APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby APOD Robot » Tue Feb 21, 2017 5:05 am

Image An Active Night over the Magellan Telescopes

Explanation: The night sky is always changing. Featured here are changes that occurred over a six hour period in late 2014 June behind the dual 6.5-meter Magellan Telescopes at Las Campanas Observatory in Chile. The initial red glow on the horizon is airglow, a slight cooling of high air by the emission of specific colors of light. Bands of airglow are also visible throughout the time-lapse video. Early in the night, car headlights flash on the far left. Satellites quickly shoot past as they circle the Earth and reflect sunlight. A long and thin cloud passes slowly overhead. The Small Magellanic Cloud rises on the left, while the expansive central band of our Milky Way Galaxy arches and pivots as the Earth rotates. As the night progresses, the Magellan telescopes swivel and stare as they explore pre-determined patches of the night sky. Every night, every sky changes differently, even though the phenomena at play are usually the same.

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Peter614

Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby Peter614 » Tue Feb 21, 2017 6:01 am

Seems like a lot of traffic near the telescopes (especially towards the end of the clip). Would that affect the results from the observation?. Thinking about the light pollution from headlights & tailights, as well as the dust kicked up by the cars.

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby kenkahn » Tue Feb 21, 2017 10:19 am

All I see on my desktop is cat sleeping on a ledge next to a laptop. I understand that this is the 'alternate' picture when the APOD is a video. I'm just curious where do these pictures come from and who decides which one to d/l as the desktop?

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby geckzilla » Tue Feb 21, 2017 12:04 pm

kenkahn wrote:All I see on my desktop is cat sleeping on a ledge next to a laptop. I understand that this is the 'alternate' picture when the APOD is a video. I'm just curious where do these pictures come from and who decides which one to d/l as the desktop?

The desktop wallpaper app doesn't know better than to use the first linked-to jpg, gif, or png that it finds on the APOD page. Since the video is there, it grabs the one in the description. Note also that none of us here have anything at all to do with the APOD app.
Just call me "geck" because "zilla" is like a last name.

heehaw

Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby heehaw » Tue Feb 21, 2017 2:08 pm

A good picture: of a vast galaxy AND of human 'eyes' observing it. How many more civilizations are there out there, also eyeing that galaxy? A clue is our own solar system: yes, we have an Earth with our civilization. But perhaps more important we have Venus, which has lost ALL its hydrogen and hence NO water and hence NO chance of life. The fact that a Venus appears in our solar system almost guarantees that Venuses are common throughout the galaxy. But we can NOT conclude from our own presence that Earths are similarly common. That is the remaining huge unknown: how common are Earth/Venus-size planets in the habitable zone that do NOT lose their hydrogen? We do not know. It may be that an unusual event involving the origin of our big Moon was somehow crucial to our retaining our hydrogen and therefore having lots of water, leading to life and leading to this posting. If that is so, there may only be tiny numbers of 'Earths' in our galaxy. As it stands, we just don't know! But with future space telescopes, we are going to find out, through spectroscopy of the atmospheres of planets of other stars. (Of course I'd love to have it turn out that true Earths are common.)

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby theotherkevinsmith » Tue Feb 21, 2017 3:22 pm

Is that a Roll Cloud that crosses the sky in arriving at :04 seconds and continuing to about :08 seconds?

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby RJN » Tue Feb 21, 2017 4:07 pm

An emailer claims that I have mis-identified the SMC as the LMC. After some preliminary checking that seems quite possible. Would someone be kind enough to double check this? - RJN

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby geckzilla » Tue Feb 21, 2017 4:30 pm

RJN wrote:An emailer claims that I have mis-identified the SMC as the LMC. After some preliminary checking that seems quite possible. Would someone be kind enough to double check this? - RJN

I agree, it's the SMC. LMC must be behind the telescope the whole time.
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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby RJN » Tue Feb 21, 2017 7:37 pm

geckzilla wrote:I agree, it's the SMC. LMC must be behind the telescope the whole time.


Thanks! SMC it is. I updated the main NASA APOD. My apologies to everyone - RJN

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby BDanielMayfield » Tue Feb 21, 2017 8:52 pm

heehaw wrote:A good picture: of a vast galaxy AND of human 'eyes' observing it. How many more civilizations are there out there, also eyeing that galaxy? A clue is our own solar system: yes, we have an Earth with our civilization. But perhaps more important we have Venus, which has lost ALL its hydrogen and hence NO water and hence NO chance of life. The fact that a Venus appears in our solar system almost guarantees that Venuses are common throughout the galaxy. But we can NOT conclude from our own presence that Earths are similarly common. That is the remaining huge unknown: how common are Earth/Venus-size planets in the habitable zone that do NOT lose their hydrogen? We do not know. It may be that an unusual event involving the origin of our big Moon was somehow crucial to our retaining our hydrogen and therefore having lots of water, leading to life and leading to this posting. If that is so, there may only be tiny numbers of 'Earths' in our galaxy. As it stands, we just don't know! But with future space telescopes, we are going to find out, through spectroscopy of the atmospheres of planets of other stars. (Of course I'd love to have it turn out that true Earths are common.)


I'd love for really earth-like exo-Earths to be common to, but alas, it don't appear to be so. Some think that having a gas giant or two out in orbits like Jupiter and Saturn also play roles in making our planet so inhabitable (and not just habitable :ssmile:) One survey of 1,122 sunlike stars found only one gas giant out in a Jupiter like orbit.

Bruce
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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby BDanielMayfield » Tue Feb 21, 2017 9:08 pm

But, (always trying to look on the bright side) Super-Earths and Ice Giants look to be very common. Earth-like moons of such planets could be out thar, dag nag it. Hope remains ...

Bruce
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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby MarkBour » Tue Feb 21, 2017 9:38 pm

BDanielMayfield wrote:I'd love for really earth-like exo-Earths to be common to, but alas, it don't appear to be so. Some think that having a gas giant or two out in orbits like Jupiter and Saturn also play roles in making our planet so inhabitable (and not just habitable :ssmile:) One survey of 1,122 sunlike stars found only one gas giant out in a Jupiter like orbit.
Bruce

Bruce, can you elaborate on the notion of our needing gas giants? I certainly have seen things that made me realize that Jupiter is a godsend for us, but did not realize there would be other issues and cases that multiple large planets are helpful for. Thanks.
Mark Goldfain

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby BobStein-VisiBone » Tue Feb 21, 2017 10:51 pm

To my eyes the reddish airglow appears to be "moving" in spurts. Not smooth motion as the stars and horizon. Illusion? Artifact? Or a real phenomenon?

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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby BDanielMayfield » Tue Feb 21, 2017 11:17 pm

MarkBour wrote:
BDanielMayfield wrote:I'd love for really earth-like exo-Earths to be common to, but alas, it don't appear to be so. Some think that having a gas giant or two out in orbits like Jupiter and Saturn also play roles in making our planet so inhabitable (and not just habitable :ssmile:) One survey of 1,122 sunlike stars found only one gas giant out in a Jupiter like orbit.
Bruce

Bruce, can you elaborate on the notion of our needing gas giants? I certainly have seen things that made me realize that Jupiter is a godsend for us, but did not realize there would be other issues and cases that multiple large planets are helpful for. Thanks.

First off I just learned that the 1122 star survey I mentioned had 8 Jupiter analogs, but included one newly discovered planet. They estimated that only 3% of sunlike stars have a Jupiter like planet.

Mark, as you may well know a great many hot Jupiters have been found. If they spiraled in they would have been disasterous for any earth like planet. Jupiter may have stayed in the outer parts of the solar system because of the presence of Saturn. You should look up the Nice Model to see how mighty Jupiter and his sidekick Saturn may have muscled the other planets around and lead to the Late Heavy Bombardment.

Bruce
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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby BDanielMayfield » Wed Feb 22, 2017 12:20 am

Continuing... the LHB would have replaced the heavier elements in the Earth's crust that would have sank into the Earth's interior at earlier, more molten epochs. It also could have delivered more water to the planet, but the notion that our water largely came from impactors is questioned lately.

There is also the idea that Jupiter may serve a protective role, deflecting or catching objects that might otherwise hit the Earth. I think this notion is debated also though.

Bruce
Last edited by BDanielMayfield on Wed Feb 22, 2017 4:50 am, edited 1 time in total.
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Re: APOD: An Active Night over the Magellan... (2017 Feb 21)

Postby BDanielMayfield » Wed Feb 22, 2017 12:41 am

heehaw wrote:A good picture: of a vast galaxy AND of human 'eyes' observing it. How many more civilizations are there out there, also eyeing that galaxy? A clue is our own solar system: yes, we have an Earth with our civilization. But perhaps more important we have Venus, which has lost ALL its hydrogen and hence NO water and hence NO chance of life. The fact that a Venus appears in our solar system almost guarantees that Venuses are common throughout the galaxy. But we can NOT conclude from our own presence that Earths are similarly common. That is the remaining huge unknown: how common are Earth/Venus-size planets in the habitable zone that do NOT lose their hydrogen? We do not know. It may be that an unusual event involving the origin of our big Moon was somehow crucial to our retaining our hydrogen and therefore having lots of water, leading to life and leading to this posting. If that is so, there may only be tiny numbers of 'Earths' in our galaxy. As it stands, we just don't know! But with future space telescopes, we are going to find out, through spectroscopy of the atmospheres of planets of other stars. (Of course I'd love to have it turn out that true Earths are common.)


As Mark asked me about the need for gas gaints I ask you also, why do you think Venus was important for Earth's habitablity? Is she really needed, or is she mearly ornamental?
"Happy are the peaceable ... "


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