Astronomy Related

Meem

25th July 2009 - 03:24 AM

So, I have seen a few shooting stars before. They more or less look like a streak, which has to do with the speed that they are traveling at. While I was camping I saw something which I have seen before and I assume that it is a falling star. I was looking up and I saw what looked like a star moving, but it wasn't streaking or gone in the blink of an eye. It lasted a few seconds but over the entire process, the star seemed to fade out from a bright white dot to a red/orange one before "disappearing." It took about 4-5 seconds it seems.

I just assume, this to be "space-junk" (man made or natural) that falls into orbit at a slower velocity? If the trajectory was directly at your particular frame of reference, this could also appear to be as a star just "going out?"

flyingbuttressman

25th July 2009 - 03:31 AM

I may be mistaken, but I believe that I've seen a satellite in orbit. It was a solid light that moved slowly against the backdrop of stars. I'm pretty sure that it was too slow to be a plane, and too high to be a helicopter.

Meem

25th July 2009 - 03:39 AM

See, I used to think that too but, I mean ... what are the chances of seeing a bus or car from that far away even if the "headlights" are on?

QUOTE

Distance for Geosynchronous Orbit
Kepler's third law allows us to calculate the distance from the center of the Earth for a geosynchronous orbit. Kepler's third law is a mathematical equation relating the orbital period, orbital radius, and the mass of the Earth or other object being orbited. See the illustration for the mathematical details. Using Earth's rotational period in seconds and Earth's mass in kilograms gives a value of 42,200 kilometers (or 26,200 miles) for the distance a satellite has to be from the center of the Earth to orbit geosynchronously. Subtracting Earth's radius gives a distance from Earth's surface of 35,900 kilometers or 22,300 miles.

Heck, I can barely read a sign 50 feet away with glasses on, you know?

(edit)
I say car or bus because I think that's the comparative size of satellites and the headlights being on makes fora good analogy. I'm not trying to be a smartass by putting this up either, just trying to clarify my line of thought as best I can.

flyingbuttressman

25th July 2009 - 03:50 AM

Who said it was in geosynchronous orbit? It was moving, which means that it wasn't in geosynchronous orbit. Low orbit is only a few hundred miles up, though it is probably more likely that it was a high-altitude aircraft.

Meem

25th July 2009 - 03:56 AM

Can't satellites move in geosynchronous orbit? I mean, I don't know it doesn't seem like satellites would last very long in low orbit. It would require a whole bunch of fuel for them to move around in low orbit like that. Was also under the impression that's why they aren't moved too often, when in geosync, and the use of them falls into windows of opportunity.

flyingbuttressman

25th July 2009 - 04:02 AM

QUOTE (Meem+Jul 24 2009, 10:56 PM)

Can't satellites move in geosynchronous orbit? I mean, I don't know it doesn't seem like satellites would last very long in low orbit. It would require a whole bunch of fuel for them to move around in low orbit like that. Was also under the impression that's why they aren't moved too often, when in geosync, and the use of them falls into windows of opportunity.

Geosynchronous means that it sits above one point on Earth and orbits at the same rate that Earth does, aka 1 revolution every 24 hours.

Low orbit is mostly outside the atmosphere. There is a small small amount of atmosphere there, but only enough to slow things down over long periods of time. Objects in this orbit can go around the world up to 16 times each day.

Technically, once orbit is achieved, very little fuel should be required. The only fuel needed is fuel for course correction and a small amount to counteract a small amount of drag.

uaafanblog

25th July 2009 - 04:03 AM

Here is a definition of the various orbits used by satellites. Many many orbit less than 300 miles from the surface.

I have seen the Space Shuttle go by ... I have seen weather satellites as well. Many many people can see the ISS just about any night.

flyingbuttressman

25th July 2009 - 04:06 AM

QUOTE (uaafanblog+Jul 24 2009, 11:03 PM)

Here is a definition of the various orbits used by satellites. Many many orbit less than 300 miles from the surface.

I have seen the Space Shuttle go by ... I have seen weather satellites as well. Many many people can see the ISS just about any night.

I figured that I would explain it gently before I tore him a new one.

Meem

25th July 2009 - 04:16 AM

So, then why would it not cross the "whole" sky? And what are their speeds? this was moving very slow, so I would assume further away, perceptively. The actual "sky-space" it took place in was relatively small, say about as many degrees as it seemed to last, about 4-5 out of 180?

I have seen what I thought were satellites etc, they move pretty fast compared to what I am talking about.

flyingbuttressman

25th July 2009 - 04:19 AM

QUOTE (Meem+Jul 24 2009, 11:16 PM)

So, then why would it not cross the "whole" sky? And what are their speeds? this was moving very slow, so I would assume further away, perceptively. The actual "sky-space" it took place in was relatively small, say about as many degrees as it seemed to last, about 4-5 out of 180?

I have seen what I thought were satellites etc, they move pretty fast compared to what I am talking about.

I'm not ruling out that it was a meteor or a satellite. An object orbiting the Earth could have turned the lights on, then off. There's no way to nail down exactly what you saw. The speed, however, seems to rule out a meteor, saving some trick of perspective (foreshortening).

AlexG

25th July 2009 - 04:20 AM

QUOTE

So, then why would it not cross the "whole" sky? And what are their speeds? this was moving very slow, so I would assume further away, perceptively.

If it was heading more or less directly at you, you would see very little apparent transverse movement.

flyingbuttressman

25th July 2009 - 04:23 AM

QUOTE (AlexG+Jul 24 2009, 11:20 PM)

If it was heading more or less directly at you, you would see very little apparent transverse movement.

If only it was a meteorite, instead of just a meteor.

Meem

25th July 2009 - 04:32 AM

I have to lean towards meteorite or "junk" because of the fade effect I noticed. If it were something "turning the lights on then off," I doubt I would see the reddish glow of the "light-bulb" near the end ... you know?

AlexG

25th July 2009 - 04:37 AM

QUOTE

If only it was a meteorite, instead of just a meteor.

It's a metorite once it lands, if it does. As long as it's air(space) born, it's a meteor.

What you saw, Meem, was probably a fireball. If instead of fading out, it had exploded into several pieces, it would be called a bolide.

http://www.amsmeteors.org/fireball/faqf.html#1

I saw a spectacular bolide back in 1965, while sitting at a drive-in theater. It was just dusk, the show hadn't started yet, and the bolide passed directly above the drive-in screen. It appeared to last 3 or 4 seconds, and exploded in a bright flash. The news the next day said it was probably the size of a large suitcase.

Alienbeing

19th August 2009 - 04:31 AM

QUOTE (Meem+Jul 25 2009, 03:39 AM)

See, I used to think that too but, I mean ... what are the chances of seeing a bus or car from that far away even if the "headlights" are on?

Heck, I can barely read a sign 50 feet away with glasses on, you know?

(edit)
I say car or bus because I think that's the comparative size of satellites and the headlights being on makes fora good analogy. I'm not trying to be a smartass by putting this up either, just trying to clarify my line of thought as best I can.

Oh of course you can see Satellites on a clear night, I see many of them. They are extremely high up and move at a precise speed, sometimes the will brighten as they move catching more of the suns reflection. But make no mistake you can absolutely see them all night long. Some Geo types track on the equator at the same speed as the earth rotates...so they appear stationary but all Satellites need to move or they would fall back to earth. You can also see the Space station which is very bright compared to most anything in the night sky.

MjolnirPants

19th August 2009 - 06:05 AM

I dunno if anyone would think this is interesting or not, but I once saw a meteor streak by me so closely I could hear it. I could even see that the flames were multicolored, which was extraordinarily odd, considering that AFAIK most meteors are composed of only a few substances. This one had red, green, blue and purple flames, indicating a wide variety of substances.

And yes, it has occurred to me that it might have been part of an old satellite.

dakfe09

19th August 2009 - 09:36 AM

did you look for any fragments?

MjolnirPants

20th August 2009 - 01:20 AM

QUOTE (dakfe09+Aug 19 2009, 04:36 AM)

did you look for any fragments?

I watched it disintegrate in the sky. There would have been no fragments to find.

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