APOD: Geminid Meteors over Chile (2019 Dec 08)

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APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by APOD Robot » Sun Dec 08, 2019 5:07 am

Image Geminid Meteors over Chile

Explanation: Are meteors streaming out from a point in the sky? Yes, in a way. When the Earth crosses a stream of Sun-orbiting meteors, these meteors appear to come from the direction of the stream -- with the directional point called the radiant.  An example occurs every mid-December for the Geminids meteor shower, as apparent in the featured image.  Recorded near the shower's peak in 2013, the featured skyscape captures Gemini's shooting stars in a four-hour composite from the dark skies of the Las Campanas Observatory in Chile. In the foreground the 2.5-meter du Pont Telescope is visible as well as the 1-meter SWOPE telescope. The skies beyond the meteors are highlighted by Jupiter, seen as the bright spot near the image center, the central band of our Milky Way Galaxy, seen vertically on the image left, and the pinkish Orion Nebula on the far left. Dust swept up from the orbit of active asteroid 3200 Phaethon, Gemini's meteors enter the atmosphere traveling at about 22 kilometers per second. The 2019 Geminid meteor shower peaks again this coming weekend.

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orin stepanek
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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by orin stepanek » Sun Dec 08, 2019 12:35 pm

I sometimes wonder if space debris add much to the weight of a planet? Of coarse we probably lose as much with all the space junk we put in orbit! :mrgreen:
Orin

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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by neufer » Sun Dec 08, 2019 1:20 pm

orin stepanek wrote:
Sun Dec 08, 2019 12:35 pm

I sometimes wonder if space debris add much to the weight of a planet?
https://en.wikipedia.org/wiki/Micrometeorite wrote:
<<An estimated 40,000 ± 20,000 tonnes per year (t/yr) of cosmic dust enters the upper atmosphere each year of which less than 10% is estimated to reach the surface as particles. Therefore, the mass of micrometeorites deposited is roughly 50 times higher than that estimated for meteorites, which represent approximately 50 t/yr, and the huge number of particles entering the atmosphere each year (~1017 > 10 µm) suggests that large MM collections contain particles from all dust producing objects in the Solar System including asteroids, comets, and fragments from our Moon and Mars. Large MM collections provide information on the size, composition, atmospheric heating effects and types of materials accreting on Earth while detailed studies of individual MMs give insights into their origin, the nature of the carbon, amino acids and pre-solar grains they contain.

Fewer than 1% of MMs are achondritic and are similar to HED meteorites, which are thought to be from the asteroid, 4 Vesta. Most MMs are compositionally similar to carbonaceous chondrites, whereas approximately 3% of meteorites are of this type. The dominance of carbonaceous chondrite-like MMs and their low abundance in meteorite collections suggests that most MMs derive from sources different than those for most meteorites. Since most meteorites probably derive from asteroids, an alternative source for MMs might be comets. Analyses of particles returned from the comet, Wild 2, by the Stardust spacecraft show that these particles have compositions that are consistent with many micrometeorites.

The influx of micrometeoroids also contributes to the composition of regolith (planetary/lunar soil) on other bodies in the Solar System. Mars has an estimated annual micrometeoroid influx of between 2,700 and 59,000 t/yr. This contributes to about 1m of micrometeoritic content to the depth of the Martian regolith every billion years. Measurements from the Viking program indicate that the Martian regolith is composed of 60% basaltic rock and 40% rock of meteoritic origin. The lower-density Martian atmosphere allows much larger particles than on Earth to survive the passage through to the surface, largely unaltered until impact. While on Earth particles that survive entry typically have undergone significant transformation, a significant fraction of particles entering the Martian atmosphere throughout the 60 to 1200-μm diameter range probably survive unmelted.>>
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Ann
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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by Ann » Sun Dec 08, 2019 1:41 pm

orin stepanek wrote:
Sun Dec 08, 2019 12:35 pm
I sometimes wonder if space debris add much to the weight of a planet? Of coarse we probably lose as much with all the space junk we put in orbit! :mrgreen:
Good question, Orin! :D

I didn't fully understand Art's answer, but I appreciated it anyway. But, Orin, I think you're wrong that Earth is losing weight with all the space junk we put in orbit. It will all eventually come down again, won't it?

So with so much debris being deposited on the Earth, and our dear old planet not shedding any of its pounds, I guess mother Earth is putting on weight and plumping up, isn't she?

Except she is pretty plump already. That's okay, dear planetary Mama, we love you just the way you are!

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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by TRImmoos » Sun Dec 08, 2019 1:44 pm

Composite image. 4 hours of meteors but no star trails.

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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by neufer » Sun Dec 08, 2019 2:00 pm

Ann wrote:
Sun Dec 08, 2019 1:41 pm

Orin, I think you're wrong that Earth is losing weight with all the space junk we put in orbit. It will all eventually come down again, won't it?
  • There is a lot of rocket fuel that's Gone with the Solar Wind.

    Also:
https://en.wikipedia.org/wiki/List_of_Solar_System_probes wrote:
<<This is a list of space probes that have left Earth orbit, organized by their planned destination. It includes planetary probes, solar probes, and probes to asteroids and comets, but excludes lunar missions, which are listed separately at List of lunar probes and List of Apollo missions.>>
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Chris Peterson
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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by Chris Peterson » Sun Dec 08, 2019 2:29 pm

Ann wrote:
Sun Dec 08, 2019 1:41 pm
But, Orin, I think you're wrong that Earth is losing weight with all the space junk we put in orbit. It will all eventually come down again, won't it?
The vast majority of the mass of launches is in rocket fuel that never leaves the Earth at all. Most of what we launch will, in fact return. And what doesn't is a small fraction of the mass of the meteorites and interstellar dust that bombard us continuously- thousands of tons per year, and the occasional 1015 kg impactor every 100 million years or so. And we've only been sending anything into space for less than a century, and may not be doing so for more than another.

I don't think Earth's diet plan should depend upon us!
Chris

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Ann
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Re: APOD: Geminid Meteors over Chile (2019 Dec 08)

Post by Ann » Sun Dec 08, 2019 4:33 pm

I was going to say when I saw this APOD that Jupiter is very photogenic almost right in the middle of the radiant, so that it almost looks like a precious stone blasting sparkles all around it! Hey Jupiter, watch out so you don't get meteor dust in your face. (Except you don't, right? Since, just because the Earth is crossing the dust-strewn path of that old comet whatsitsname any day now doesn't mean that Jupiter is crossing that cometary path at the same time as we do, right?)

I was also going to say, look how beautiful the Pleiades are to the upper right of Jupiter! Except that, no, that's not the Pleiades. That's the Beehive cluster. The Seven Sisters are just above the horizon at far left in the APOD.

Ann
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