Mysterious Flash in the Sky - Ask PF Community

[Siberion]

Hello, PF community.

Past wednesday I was visiting the National Astronomical Observatory, which is located pretty close to my home, in Chile. It was about 10 pm, and I was waiting for my turn to see through the main telescope, while some astronomers were teaching us about the common stars in the nightsky.

I was looking at certain place in the sky, near Sirius, when all of sudden I saw a tiny dot in the sky, which disappeared in less than a second. It was a really short flash, which brightness and apparent size was comparable to a star. It didn't describe a curve or a straight line, it simply flashed and disappeared. Then, after 3 seconds, I saw another one, exactly equal to the last one, but it appeared a bit more to the west than the previous one.

I kept waiting for more, but that was all. As the astronomers were busy talking to other people, I forgot to ask them about it. this may be a very common event but I'm not really sure of what could it be. So the question is:

Do shooting stars always describe a curve when seen on the sky?. The flashes I saw were not exactly located on top of me, so if it was in fact a shooting star, wdouln't it have described a movement different than a single point?.

I'm sorry if this seems too obvious.
Thanks!

 

[Pengwuino]

So you're saying you saw a flash of light that didn't actually appear to travel like a meteorite would?

 

[Siberion]

That's what I think, as far as my knowledge goes. Whenever I've seen a meteor in the nightsky entering the atmosphere, it has described either a curve or a straight line in the sky from my point of view. But that's essentially what I'm asking, is it possible for meteors to just appear as a tiny bright dot in the sky which only lasts a fraction of a second?. Perhaps a really small one would do the job.

 

[DaveC426913]

That's what I think, as far as my knowledge goes. Whenever I've seen a meteor in the nightsky entering the atmosphere, it has described either a curve or a straight line in the sky from my point of view. But that's essentially what I'm asking, is it possible for meteors to just appear as a tiny bright dot in the sky which only lasts a fraction of a second?. Perhaps a really small one would do the job.

It's possible. One, maybe, but two is unlikely.
You could have seen a meteor burning up while coming directly toward you.

But I'd look for other explanations. Why couldit not have been a slow-moving helicopter.

 

[Siberion]

But I'd look for other explanations. Why couldit not have been a slow-moving helicopter.

I sincerely doubt it was an helicopter. The light was white/blue, such as the brightest stars on the sky, and it didn't seem as artificial as airplanes or helicopters light. Also, considering the size of the dot, it appeared to flash at much higher altitude (I know jumping to these conclusions can be tricky especially at nightsky w/ naked eye, but the light seemed to be different), and it'd have taken a bit longer for an helicopter to get from point A to point B in the given 3 seconds.

I'm not fully discarding this option, because my eyes are not sensible enough to distinguish such measurements with a high precision, but it really seemed to be something getting in contact with the atmosphere and burning. What about space junk? Is that even possible?

 

[Chronos]

Telescopes can be tricky, you may have seen lens flares. The short duration draws me to this conclusion.

 

[mikegem]

You might have seen an Iridium flare. The Iridium satellites provide predictable, extremely bright transient flashes. You can learn more about them at http://en.wikipedia.org/wiki/Satellite_flare

and

http://www.heavens-above.com/

The latter site will display time and location of Iridium flares if you input your observing location.

 

[phyzguy]

You might have seen an Iridium flare. The Iridium satellites provide predictable, extremely bright transient flashes.

I agree this sounds like what you saw. It could have been either from the Iridium satellites or from some other satellite. The solar panels are pretty reflective, and for a brief time they can be in the right orientation to reflect sunlight in your direction. If it had two panels that were slightly offset, that might be why you saw two flashes.

 

[Borek]

Iridium flares are not point like flashes, you can see them traveling. They are much slower then your usual meteorite, but there is no doubt they move.

 

[Jack21222]

Do they have fireflies in Chile? I was once baffled by a firefly up over my head while stargazing.

 

[DaveC426913]

Telescopes can be tricky, you may have seen lens flares. The short duration draws me to this conclusion.

Wait. What?

Siberion: were you looking through a telescope when this happened? That is not what I read.

...I was waiting for my turn to see through the main telescope...

 

[DaveC426913]

...I saw a tiny dot in the sky, which disappeared in less than a second. It was a really short flash, which brightness and apparent size was comparable to a star. It didn't describe a curve or a straight line, it simply flashed and disappeared.

Then, after 3 seconds, I saw another one, exactly equal to the last one, but it appeared a bit more to the west than the previous one.

Siberion, this sounds like a satellite with an unusually short, intermittent flash.

If the flash was as short as you say, it might have been too short for you to notice that it was moving. Then a few seconds later, it would have flashed again a bit further along its path.

 

[Siberion]

Do they have fireflies in Chile? I was once baffled by a firefly up over my head while stargazing.

Not in the place I live in. Probably the most exciting thing you can find around here are common pigeons

Telescopes can be tricky, you may have seen lens flares. The short duration draws me to this conclusion.

Actually, I was waiting for my turn to see through the telescope, so I visualized this event with naked eye.

Siberion, this sounds like a satellite with an unusually short, intermittent flash.

If the flash was as short as you say, it might have been too short for you to notice that it was moving. Then a few seconds later, it would have flashed again a bit further along its path.

This looks like a really convincing answer. The only thing I'd still be wondering about is why it only flashed two times during the time I was observing. That seemed rather unusual. If it was at least 3 or more flashes, I could more or less link them up and approximate the path of the satellite...

 

[Borek]

Places where the reflected beam can be seen are on the helicoid, it is rather surprising you have seen it more than once.

 

[DaveC426913]

Places where the reflected beam can be seen are on the helicoid, it is rather surprising you have seen it more than once.

Wwwwwhat? What beam? What helicoid? What drugs?

 

[Borek]

I am thirsty as a toddler.

What is the source of satellite flashes?

 

[DaveC426913]

I am thirsty as a toddler.

What is the source of satellite flashes?

Sunlight off rotating reflective surfaces?

OK, so the helicoid you're talking about relates to a satellite's orientation as it rotates along its path. (I think that required a little more context. Heck, you could have been talking about helicopter blade motion...)

But I don't think reflections create a narrow "beam". If it's only moved a few seconds farther along its path, it's not like the "beam" is going to be collimated to just a fraction of a degree.

 

[Borek]

Sure, satellite solar panels they are not perfectly flat and the light gets diffracted and dispersed in the air, so it is not perfectly narrow, more like some kind of a cone. Also a lot depends on the rotational period of the satellite. But simplified geometry is just a helicoid.

Now that I think about it it can be an interesting problem. When you look at Iridium flares you see two things - satellite motion (as it traverses the sky) and rotation (that is, brightness of the reflection first goes up, then goes down). Perhaps it is possible to predict how many flashes could be seen - as a function of both orbital and rotational speed of the satellite. Iridium satellites rotate rather slowly, so there is only one long flash visible, but if they would rotate ten times faster, my picture would probably look like a chain of dashes.