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I just seen a star disappear?


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#1 geko

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Posted 25 March 2009 - 02:10 PM

I was just oustide looking up at the sky and seen what i thought at the time was a disappearing star. It was a relatively bright one and as i was looking at it, it got dimmer and dimmer until it was gone. Took like 5 seconds or so to completely disappear from what i could see.

Star disappearring seems a little far-fetched i thought, so was thinking of ways that it could or couldnt have been but have no idea where im coming from really. How likely is it? Once in a lifetime i would imagine but dont know.

It wasnt the space station as that was in the sky at the same time. The star was kind of in the path of the satellite so i thought that maybe it was reflecting light off of something, and as the angles changed the light changed path and that's what i seen? No idea.

No clouds in the sky.

What do you make of it?

#2 freeztar

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Posted 25 March 2009 - 02:26 PM

Did you note it's location? What constellation was it in/near? What was the closest known star to use as a reference and how many degrees away was it and in what direction?

I've never heard of a star suddenly disappearing from view. My guess is that it has something to do with atmospheric/optical effects.

#3 CraigD

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Posted 25 March 2009 - 03:27 PM

It is possible for a celestial object to disappear – that is, starting above the minimum apparent luminosity to be seen with the naked eye, reduce luminosity to below it – but your description – from relatively bright to invisible in 5 seconds – doesn’t sound to me like it could be an observation of a distant celestial object.

Supernovae are among the fastest changing celestial objects, fairly blinking into and out of observability as astronomers measure such things, but even they take about 14 days to decrease 1 magnitude (a factor of about 2.5) in luminosity (see Supernovae Light Curves.). “Relatively bright” corresponds to a magnitude between -1 and 1, while the limit of naked eye visibility is about 3, so if what you were observing was a fading supernova, it would have taken about a month to disappear, many times longer than the 5 seconds you report.

From a astrophysics perspective, I can’t imagine any natural process that could dim this fast. The most violent things that can “put stars out” – exploding as supernovae, being sucked into black holes, etc. – take at least days to effect the luminosity change you observe, while things that can obscure them, such as dust and gas clouds, take millennia to move between us and a star. I can imagine how some sort of super-advanced engineering project, such as building a Dyson sphere, might abruptly cut off the light from a star, but this seems extremely unlikely.

The most plausible explanation I can imagine is that what you saw, geko, was either a meteor, an aircraft light, or, as you speculated, the reflection from a satellite.

If you’re driven to find more definite confirmation, I recommend you contact an observatory – going through the information offices of a university near you is a good approach – to see if they have any images of the sky where and spanning the time when you observed your weird thing. If a bright star actually disappeared, it should be obvious on such an image. If the star blinked into visibility as quickly as you speculate it may have blinked out, this approach is likely useless, but as you didn’t report that, we can assume the hypothesized star was around for a long time prior to its disappearance.

You mention that it appeared near the ISS. Do you have a precise, accurate time of your observation? From this and your ground position, it should be easy for a pro astronomer to locate the required images.

#4 geko

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Posted 26 March 2009 - 05:04 AM

Interesting.

I guess it doesnt sound like a star disappearing then. No i dont really have an accurate time for it, it was about 9 pm. From my prespective i think im certain sure it wasnt an aeroplance or meteor as ive never mistaken an aeroplace for a star before, and it wasnt moving which made me think it wasnt a meteor, but yeah could be either of course. If only i could plug into something so i could watch it again :lol:

It would be nice to find out, maybe i will contact the local uni.

#5 Pyrotex

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Posted 26 March 2009 - 08:39 AM

hi geko,
I've been an amateur astronomer for 50 years now, and I've seen a couple of events like you described.
Once my brothers and I were "camping out" in the back yard, lying on our backs, looking up into a clear totally black sky. Suddenly, we saw a star appear, get very bright (like Jupiter) and then fade to nothing, over a span of ten seconds or so.
It was an ordinary meteorite, except that its path was pointed directly at our back yard!
I have seen glints from Iridium satellites on two occassions, because I looked up "Iridium glints" online and found a schedule of when and where they occurred. :lol:
Of course, I've seen satellites, looking no brighter than an ordinary star, fade to zero as it passed into the Earth's shadow, but it was also moving. You didn't say whether or not your "star" was moving.
I can say without reservations that there is no known or plausible mechanism for a star of any kind to suddenly fade and vanish over seconds or minutes.
However... there is ONE way for a star to SEEM to vanish. Occultation.
Perhaps an asteroid, maybe just a few kilometers wide, maybe just half a million miles away, precisely occulted the star you were looking at. You would never see the asteroid of course. And if you waited five minutes, the star would have reappeared.
Not likely, but possible. :evil:

#6 modest

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Posted 26 March 2009 - 08:57 AM

It's not uncommon for satellites to disappear mid-sky. They reflect the sun's light until the sun sets on the satellite (where the earth is between the sun and satellite). When I've seen this happen they do indeed appear to fade to black over a couple to a few seconds depending on how fast they're moving. You can search your location and the date and time of the sighting on either of these NASA sky trackers:

NASA - Science@NASA JPass
Human Space Flight (HSF) - Realtime Data

They use JAVA. On the first link if you get something like this:

Posted Image

where the green line turns purple the satellite will disappear. The purple path is in shadow, so it'll look like a disappearing star except that it's moving. But, I suppose you might not notice its motion if you're not observing it for long.

That would be my guess.

~modest

#7 CraigD

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Posted 26 March 2009 - 11:54 AM

However... there is ONE way for a star to SEEM to vanish. Occultation.
Perhaps an asteroid, maybe just a few kilometers wide, maybe just half a million miles away, precisely occulted the star you were looking at. You would never see the asteroid of course. And if you waited five minutes, the star would have reappeared.
Not likely, but possible.

This is an interesting explanation. ;)

I’d considered it, but guessed that such occultation events would be so brief they’d seem “twinklings” rather than with long enough durations to be “disappearances”. Doing a little research revealed the nifty website www.asteroidoccultation.com, from which, looking at its data for the year of 2008, I learned that asteroid occulted stars are mostly too dim to be seen with the naked eye and/or occulted so briefly that the event would be perceived as twinkling. The only asteroid occultation event recorded for a star brighter than magnitude 3, which is usually considered the limit of naked eye observation, was Aug 25, 16:45, a 2.6 mag start occulted for 0.8 s. The longest occultation of a star brigher than mag 4 was Oct 22, 23:45, a 3.7 mag star occulted for 2.9 s. There were some long duration occultations, but they were of dim stars, such as a Sep 10, 13:06 occulting of a 13.7 mag star for 188.5 s, but the brightest star occulted for at least 5 s was a 4.4 mag one on Jun 15, 13:15.

In short, it appears that most asteroid occultations are much too dim to be seen without a telescope, while those that are bright enough to be seen are too brief to be perceived as a disappearance. None recorded in 2007 at Asteroidoccultation.com were of start bright enough to be described as “relatively bright”.

Asteroidoccultation.com has a FAQ page with a good overview of asteroid occultation, including links to related websites, which explains how asteroid occultation observations have provided a lot of information about the dimensions of asteroids.

#8 geko

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Posted 26 March 2009 - 12:59 PM

Posting before ive looked at any of the links provided but i did think it could be occultation (although i didnt know that word until now), so i stayed outside for about 20 mins i guess waiting for it to reappear but it never did. I also thought maybe it was a planet moving in the way but i had no idea how long id have to wait until that moved out the way so i left it alone.

I guess the total time that i knew the star was there was a little under a minute, as i was watching the space station go across the sky and the star was to the left of it for a while but pretty bright so was catching my eye. I then turned my attention to the star and it then disappeared a few moments later.

Going to take a look at those satellite links.

#9 CraigD

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Posted 26 March 2009 - 01:28 PM

I also thought maybe it was a planet moving in the way but i had no idea how long id have to wait until that moved out the way so i left it alone.

I believe we can rule out a planet occulting a bright star or planet, because all such occultations have been predicted for at least the next century, and none is calculated between 1984 and 2015 (see the wikipedia article section “Occultations and transits between 1800 and 2100”).

Scrolling up one section in the linked article, there’s mention of several proposed artificial satellites designed to occult stars in very precise ways (very cool ideas, IMHO), but to my knowledge, nothing like that has yet been flown.

I’m still guessing it was a meteor, per Pyrotex’s story, a satellite reflection, or, just possibly, an unusually aircraft.

#10 lemit

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Posted 26 March 2009 - 01:39 PM

Geko, how long did you watch the sky after the star disappeared?

I've seen this exact kind of gradual (as opposed to instant) disappearance of stars many times. It has always been the result of atmospheric conditions that would be readily visible in daylight.

Geko, you need to understand that your observation is valid. But some of the explanations posted here need to have Akom's razor taken to them.

Also, anyone care to join me in the Linguistics Forum's "Misused Words" thread to discuss "meteorite?" See you there!

--lemit

#11 Shun

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Posted 17 April 2009 - 05:59 PM

ok i just saw something similar to TS... googled for answers and found this site. so i'd just share with you guys what i saw.

I just went out for morning jog, and as i'm very interested in astronomy since very young, i liked to look at the night sky... and surprisingly i witnessed something absolutely spectacular!! Just below the tail (south) of the constellation of Scorpio (near Theta Scorpii) at about 5:43am +8 GMT, i saw an extremely bright flare of light, very very bright but from only a single point, lasted very short while, 1 - 2sec before it begun to gradually dim out, dimming slowly taking another 1-2sec, flickering during the last moments and then totally disappeared. In fact i was looking elsewhere when the sudden brightness made me look up! I've seen my fair share of meteors, this bright "star" - a single point of light - remained in a stationary and fixed position, so i'm quite sure it's not a meteor. what are the chances of a meteor heading directly at me so that it looks like a single point of light? I would think extremely unlikely isn't it?

I was very amazed and kept looking around the sky long after... but no more sign of it anymore. The "star" totally disappeared. It was at least as bright as Jupiter.

anyone can tell me what i just saw?

#12 Pyrotex

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Posted 20 April 2009 - 11:55 AM

...a single point of light - remained in a stationary and fixed position, so i'm quite sure it's not a meteor. what are the chances of a meteor heading directly at me so that it looks like a single point of light?

The odds are slim but not zero. It happened to me! In a previous post I described a growing dot of stationary light almost at the zenith of a dark clear night, then fading to nothing, over maybe 10 seconds. I pointed it out to my brothers and they saw it too. We were still discussing it a few minutes later, when there was a huge metallic Ker-BANG!! from about 15 yards away. The next morning, we looked and found a one-inch dent (very deep) in our brand new garbage can lid. Unfortunately, the can was surrounded by gravel, so we never found the meteorite.

...anyone can tell me what i just saw?

Best guesses are: satellite glint, probably from the Iridium series, sun reflection off the windows of an extremely distant airliner (it was in a turn, so you only saw a short burst of light), the spontaneous annihilation caused by the collision of a red-breasted goonie bird with an anti-red-breasted goonie bird.

:magic:

#13 Titas Aduksus

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Posted 21 April 2009 - 04:58 AM

I'll go for the iridium, they appear as you say and are brief.

IF you want to see lots of fading stars take a bus to hollywood...

#14 somedanceforjoy

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Posted 26 August 2009 - 04:52 AM

Hello, It's been months since anyone has posted in this forum but I've experienced the same thing. I was searching the internet and found this just like "shun".

I was in the Mojave desert at 3am with the sky clear as can be peering out into the heavens. I noticed what i thought was another planet next to Jupiter. It was bright, about the same as Jupiter. I was about to say hey look theres another planet when suddenly it started going out. It took about three seconds until it was a small dim light. It stayed as a fixated small dim light for a few seconds and then went out. My friend came walking up and I reacted pretty crazily. He goes "did you just see a ufo"? I started to explain what just happened but he argued and said "you're just trippin", did i mention i was on lsd?
well anyways I spent hours contemplating what that could've been and reached the conclusion that i would never get to know. Frustrated, I let it go. I don't think it was meteorite, an alien, asteroid occultation, plane or a satellite. I wasn't hallucinating either. I'll never get to know.

#15 Turtle

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Posted 27 August 2009 - 06:50 PM

Hello, It's been months since anyone has posted in this forum but I've experienced the same thing. I was searching the internet and found this just like "shun".

I was in the Mojave desert at 3am with the sky clear as can be peering out into the heavens. I noticed what i thought was another planet next to Jupiter. It was bright, about the same as Jupiter. I was about to say hey look theres another planet when suddenly it started going out. It took about three seconds until it was a small dim light. It stayed as a fixated small dim light for a few seconds and then went out. My friend came walking up and I reacted pretty crazily. He goes "did you just see a ufo"? I started to explain what just happened but he argued and said "you're just trippin", did i mention i was on lsd?
well anyways I spent hours contemplating what that could've been and reached the conclusion that i would never get to know. Frustrated, I let it go. I don't think it was meteorite, an alien, asteroid occultation, plane or a satellite. I wasn't hallucinating either. I'll never get to know.


given your location away from light pollution, and presuming you have very keen vision, you may have witnessed an occultation of one of Jupiter's moons.

SkyandTelescope.com - Homepage Observing - Jupiter's Moons Dance for You!

Right now the planet Jupiter is oriented such that its equator and the orbits of its four big moons are almost exactly edge-on to the Sun and Earth. This alignment happens every six years, on opposite sides of Jupiter's 12-year orbit around the Sun.

At such times its four Galilean satellites undergo mutual phenomena: they often get occulted and eclipsed not just by big Jupiter and its shadow but also by one another. Amateur Christopher Go recently recorded a striking example of the latter.

During a mutual occultation, for example, you can watch two satellites appear to merge and, in the middle of the merger, slightly dim. During an eclipse, a lone moon fades and rebrightens as it's crossed by the shadow of one of its siblings. ...


there is video of an occultation at the link as well as more descriptions, explanations, and schedules of this phenomenon. :partycheers:

#16 pete.

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Posted 04 May 2010 - 06:21 PM

this is even weirder,i was looking out the bedroom window one stary night and felt compelled to star at three stars together,forming a triangle,the sky was full of stars nothing stood out about theses three.just 3 stars not moving,sudenly all 3 started to move in the same direction at different speeds,then thay slowly faded out one at a time,was that clouds in the way or an optical illusion,or satalites getting in the way,ill never forget it,weird.:confused:

#17 Jay-qu

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Posted 05 May 2010 - 05:40 PM

this is even weirder,i was looking out the bedroom window one stary night and felt compelled to star at three stars together,forming a triangle,the sky was full of stars nothing stood out about theses three.just 3 stars not moving,sudenly all 3 started to move in the same direction at different speeds,then thay slowly faded out one at a time,was that clouds in the way or an optical illusion,or satalites getting in the way,ill never forget it,weird.:confused:

Probably a NOSS satellite formation: NOSS Double and Triple Satellite Formations