APOD: A Perseid Below (2024 Aug 09)

[APOD Robot]

A Perseid Below

Explanation: Denizens of planet Earth typically watch meteor showers by looking up. But this remarkable view, captured on August 13, 2011 by astronaut Ron Garan, caught a Perseid meteor by looking down. From Garan's perspective on board the International Space Station orbiting at an altitude of about 380 kilometers, the Perseid meteors streak below, swept up dust from comet Swift-Tuttle. The vaporizing comet dust grains are traveling at about 60 kilometers per second through the denser atmosphere around 100 kilometers above Earth's surface. In this case, the foreshortened meteor flash is near frame center, below the curving limb of the Earth and a layer of greenish airglow, just below bright star Arcturus. Want to look up at a meteor shower? You're in luck, as the 2024 Perseid meteor shower is active now and predicted to peak near August 12. With interfering bright moonlight absent, this year you'll likely see many Perseid meteors under clear, dark skies after midnight.

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[Lasse H]

What would have happened if such a meteor as in the photo had hit the ISS?

[alex555]

To the left of Arcturus, towards the upper left edge of the image, we clearly recognize Corona Borealis, its star alpha (Alphecca) and epsilon Corona Borealis must be the site of a nova event between now and September. I watch it every night and so far, nothing.


Alex

[JohnD]

Like Lasse, this made me think of "Gravity", and not in a good way.
Good luck to the crew of the ISS, as the Perseids peak.
John

[Chris Peterson]

What would have happened if such a meteor as in the photo had hit the ISS?

It would depend where it hit. Critical parts of the ISS are protected by shields that will block particles smaller than about a centimeter. The meteor in the image was probably produced by a particle only a few millimeters in diameter, so it would have been blocked. Other areas might have sustained minor damage or pitting. The ISS is covered with such pits.

[Roy]

What would have happened if such a meteor as in the photo had hit the ISS?

I have a little experience with bullets, such as the 5.56 mm bullets fired on j13. They weigh 4.02 gm, travel at 914.4 m/sec. They will dimple 6 mm mild steel, bounce off 6 mm plow steel. According to the post, the meteors are traveling 65 times as fast. So kinetic energy is 4225 times as great. A dust grain will vaporize itself and some of the iss on impact. Anything larger than a few milligrams will be damaging.

[Chris Peterson]

What would have happened if such a meteor as in the photo had hit the ISS?

I have a little experience with bullets, such as the 5.56 mm bullets fired on j13. They weigh 4.02 gm, travel at 914.4 m/sec. They will dimple 6 mm mild steel, bounce off 6 mm plow steel. According to the post, the meteors are traveling 65 times as fast. So kinetic energy is 4225 times as great. A dust grain will vaporize itself and some of the iss on impact. Anything larger than a few milligrams will be damaging.

But the ISS does have shielding to prevent or limit damage.

[johnnydeep]

What would have happened if such a meteor as in the photo had hit the ISS?

I have a little experience with bullets, such as the 5.56 mm bullets fired on j13. They weigh 4.02 gm, travel at 914.4 m/sec. They will dimple 6 mm mild steel, bounce off 6 mm plow steel. According to the post, the meteors are traveling 65 times as fast. So kinetic energy is 4225 times as great. A dust grain will vaporize itself and some of the iss on impact. Anything larger than a few milligrams will be damaging.

What's "j13"?

[johnnydeep]

What are the several splotches of orange seen on the Earth's surface (or in it's atmosphere)? Fires? Volcanos? Lightning?

[Chris Peterson]

What are the several splotches of orange seen on the Earth's surface (or in it's atmosphere)? Fires? Volcanos? Lightning?

Cities, I'd think.

[johnnydeep]

What are the several splotches of orange seen on the Earth's surface (or in it's atmosphere)? Fires? Volcanos? Lightning?

Cities, I'd think.

Really? Hmm...

[johnnydeep]

What would have happened if such a meteor as in the photo had hit the ISS?

I have a little experience with bullets, such as the 5.56 mm bullets fired on j13. They weigh 4.02 gm, travel at 914.4 m/sec. They will dimple 6 mm mild steel, bounce off 6 mm plow steel. According to the post, the meteors are traveling 65 times as fast. So kinetic energy is 4225 times as great. A dust grain will vaporize itself and some of the iss on impact. Anything larger than a few milligrams will be damaging.

What's "j13"?

Answering my own dumb question: "j13" must be a reference to the assassination attempt on Trump on July 13, where the shooter used an AR-15 style rifle.

[Chris Peterson]

What are the several splotches of orange seen on the Earth's surface (or in it's atmosphere)? Fires? Volcanos? Lightning?

Cities, I'd think.

Really? Hmm...

Sure, why not? It's exactly the right color for the typical sodium lamp city lighting we often see on ISS shots of the night side, and it's not transient (like lightning) because it's motion streaked by the motion of the ISS.

[johnnydeep]

Cities, I'd think.

Really? Hmm...

Sure, why not? It's exactly the right color for the typical sodium lamp city lighting we often see on ISS shots of the night side, and it's not transient (like lightning) because it's motion streaked by the motion of the ISS.

Ok. They seem too concentrated and isolated, but perhaps they are islands? Not sure what area of the globe this is.

[Ann]

A Perseid Below. Image Credit: Ron Garan, ISS Expedition 28 Crew, NASA

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I guess the green layer that follows the curvature of the Earth is airglow?

I don't remember seeing airglow in similar images from previous decades. Has airglow become more common?

The Earth's limb and the Moon from ISS on 8 May, 2017. No airglow.

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The caption for this image, which was posted in 2015 and shows no appreciable airglow, reads: A NASA satellite monitors the edge of Earth to study how the planet’s atmosphere is changing.

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Noctilucent clouds in the Earth's atmosphere. The image may have been taken in 2024. Credit: Matthew Dominick from International Space Station (ISS)

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In this image from December 6, 2021, the troposphere is red and yellow from the reddened sunlight of the setting Sun. No green airglow is visible.

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Finally, you've got to check out this image that was taken on February 1, 2012, from the ISS:

Yes, there's airglow here, but it's hard to focus on the airglow with everything else going on in this image.

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Note the incredibly bright green aurora and a much fainter red aurora on top of the green one. Note the dull bronze hue of the atmosphere to the left of the aurora - is that light pollution or what? - and the faint green airglow on top of the bronze-colored layer. Note the Pleiades almost lost in the glare of the Moon. And yes, Johnny, those reddish lights on the Earth are cities.

What is that blue star at left that has been labeled "Starlight"? Is it Bellatrix? I believe that the red star between the labeled blue star and the Pleiades is Aldebaran, and Aldebaran is located about square in the middle between the Pleiades and Bellatrix.

Ann