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APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 4:06 am
by APOD Robot
The Largest Satellites of Earth
Explanation: Whatâs that near the Moon? Itâs the
International Space Station (ISS). Although the
ISS may appear to be physically near the
Moon, it is not â it is physically near the
Earth. In
low Earth orbit and circulating around our
big blue marble about every 90 minutes, the ISS was captured photographically as it crossed nearly
in front of the Moon. The Moon, itself in a month-long orbit around the Earth, shows a crescent phase as only a curving sliver of its
Sun-illuminated half is visible from the Earth. The featured image was taken in late March from
Shanghai,
China and shows not only details of Earth's largest human-made satellite, but details of the cratered and
barren surface of Earth's largest natural satellite. Over the next few years, humanity is planning to send
more people and machines to the
Moon than ever before.
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 5:10 am
by RocketRon
Marvelous photo !
Both of them would have been travelling at a fair rate of knots - in different directions ? - so capturing them in the
one image in focus must have taken some doing/precision . (As a sequence of images ? )
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 8:13 am
by Knight of Clear Skies
RocketRon wrote: ↑Mon Jun 12, 2023 5:10 am
Marvelous photo !
Both of them would have been travelling at a fair rate of knots - in different directions ? - so capturing them in the
one image in focus must have taken some doing/precision . (As a sequence of images ? )
The technique is to track the Moon (any motorized telescope mount will do this) and wait for the ISS to pass. There are websites that can tell you when and where transits will occur. Astronomers use a technique called lucky imaging to take sharp images of the Moon, Sun and planets.
[youtube]
https://youtube.com/shorts/uI-v1vtw9Pc[/youtube]
A video is taken, using software to combine the sharpest frames. If the timing is correct the ISS will shoot across the Moon or Sun rapidly, but it will show up in a few frames.
Focus isn't an issue as both the ISS and Moon are at 'infinity' focus.
Hope that helps.
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 10:21 am
by Rauf
Is it possible to capture two unrelated satellites in one frame? Like having ISS and HST in one picture together?
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 11:18 am
by De58te
Pictured are the two 'largest' satellites orbiting Earth. Out of curiosity, what is the third largest satellite around the planet Earth? The James Webb telescope? Is there any satellite bigger than the JWT?
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 12:28 pm
by orin stepanek
I think China's Space Station would be noted before the JWST!
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 1:09 pm
by Sa Ji Tario
De58te wrote: ↑Mon Jun 12, 2023 11:18 am
Pictured are the two 'largest' satellites orbiting Earth. Out of curiosity, what is the third largest satellite around the planet Earth? The James Webb telescope? Is there any satellite bigger than the JWT?
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 1:13 pm
by Sa Ji Tario
Yes, 2010 TK7 is the first discovered Trojan asteroid that accompanies the Earth's orbit around the Sun at the L4 Lagrange point of the Sun-Earth system.2 It was discovered in October 2010 by the WISE (Wide-Field Infrared Survey Explorer) space telescope. ).
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 7:54 pm
by johnnydeep
De58te wrote: ↑Mon Jun 12, 2023 11:18 am
Pictured are the two 'largest' satellites orbiting Earth. Out of curiosity, what is the third largest satellite around the planet Earth? The James Webb telescope? Is there any satellite bigger than the JWT?
I don't know which satellite might be bigger than the JWST, but the JWST actually orbits the Sun (and the L2 Lagrange point), not the Earth! See
https://jwst.nasa.gov/content/about/orbit.html for a good animation and text.
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 8:01 pm
by Chris Peterson
johnnydeep wrote: ↑Mon Jun 12, 2023 7:54 pm
De58te wrote: ↑Mon Jun 12, 2023 11:18 am
Pictured are the two 'largest' satellites orbiting Earth. Out of curiosity, what is the third largest satellite around the planet Earth? The James Webb telescope? Is there any satellite bigger than the JWT?
I don't know which satellite might be bigger than the JWST, but the JWST actually orbits the Sun (and the L2 Lagrange point), not the Earth!
From an orbital dynamics viewpoint, the same can be said for the Moon. It orbits the Sun with a tiny wiggle introduced by the Earth. If the Earth simply vanished, the Moon would sail right along in its current solar orbit with almost no change at all.
Re: APOD: The Largest Satellites of Earth (2023 Jun 12)
Posted: Mon Jun 12, 2023 8:25 pm
by johnnydeep
Chris Peterson wrote: ↑Mon Jun 12, 2023 8:01 pm
johnnydeep wrote: ↑Mon Jun 12, 2023 7:54 pm
De58te wrote: ↑Mon Jun 12, 2023 11:18 am
Pictured are the two 'largest' satellites orbiting Earth. Out of curiosity, what is the third largest satellite around the planet Earth? The James Webb telescope? Is there any satellite bigger than the JWT?
I don't know which satellite might be bigger than the JWST, but the JWST actually orbits the Sun (and the L2 Lagrange point), not the Earth!
From an orbital dynamics viewpoint, the same can be said for the Moon. It orbits the Sun with a tiny wiggle introduced by the Earth. If the Earth simply vanished, the Moon would sail right along in its current solar orbit with almost no change at all.
Hmm. From that pov then, EVERYTHING orbits the Sun! But some things are
also in orbits around other things, and some things aren't, right? I was just trying to say that the JWST does
not orbit the Earth in any sense of the term, but something else.
