APOD: How to Identify that Light in the Sky (2014 Jun 09)

[Skippy]

Well now, nothing astronomical to put here? This was useless.

[Chris Peterson]

Well now, nothing astronomical to put here? This was useless.

So was your comment.

[astrogator]

Ok my biggest gripe upon first seeing this graphic when it made its rounds in my newsfeed from IFLS was that it completely leaves out Iridium flares. Which can sometimes move a bit making it seem like a slow moving meteor as they brighten to the flare and then gradually disappear.

[geckzilla]

Well now, nothing astronomical to put here? This was useless.

So was your comment.

Actually, I think just the comment was useless. The graphic is both useful and humorous.

[Chris Peterson]

Ok my biggest gripe upon first seeing this graphic when it made its rounds in my newsfeed from IFLS was that it completely leaves out Iridium flares. Which can sometimes move a bit making it seem like a slow moving meteor as they brighten to the flare and then gradually disappear.

And some satellites blink due to rotation.

And I have to say, living at 10,000 feet in the Rockies, I've never confused a masthead light for a star. I have mistaken the light on top of Pikes Peak for star or planet more than once, however. Don't know why they didn't include that in the flow chart...

[Zuben L. Genubi]

So... lights in the sky. The morning of the Camelopardidn''t meteor storm, I was out in the country between the hours of 0300 and 0400 EST and did see, among other things, seven fairly slowly-moving, non-blinking objects. Movement was uniform in speed and direction. Most passed within several degrees of directly overhead. When I checked websites to help me identify satellites that might have passed over at that time, there might have been one listed - but not seven. All moved at about the same speed. There was no sound (such as the distant roar of jet engines that usually follows high-flying aircraft, except that of a mooing cow toward 0400 - and I don't believe that came from any of these on objects. Any ideas???

I'd assume satellites. Many more are visible than can easily be identified, both because many dimmer ones aren't tested for by identification tools, and because many are classified and don't have official elements listed (although nearly all have unofficial elements provided by amateur observers).

Thanks Chris. That's what I thought, too - but I expected more of them to be publicly acknowledged. Busy sky...

[amatastron]

Interesting and humourous. I do know a lot of people mistake Iridium flares for meteors. They flash for a few seconds, and seem to disappear. Only knowledgeable observers know to look for the much fainter satellite before and after the bight flare. Even short videos or exposures make a flare look like a meteor burning up. With that in mind, I suggest that the path be added as follows (at NEW):

"so quickly you almost missed it?"

(YES)

"is it extra super bright?"

(NO)

can you still see it moving faintly after it dimmed? (NEW)

(YES) . . . . . . . . . . . . (NO)

[FLARE] . . . . . . . [METEOR]

[kindness]

There should have at least been one out for alien spacecraft if for no other purpose than snark.

[Chris Peterson]

Well now, nothing astronomical to put here? This was useless.

So was your comment.

Actually, I think just the comment was useless. The graphic is both useful and humorous.

Quite so. I didn't mean to suggest that the APOD is useless, although it sort of came out that way.

[amatastron]

Ok my biggest gripe upon first seeing this graphic when it made its rounds in my newsfeed from IFLS was that it completely leaves out Iridium flares. Which can sometimes move a bit making it seem like a slow moving meteor as they brighten to the flare and then gradually disappear.

I agree. Just saw your post after I posted mine.

[Idaho Astro]

Seems to me that a conspicuous omission from this chart is one of the most common UFOs. I've been observing the sky for 35+ years, and the one that has taken me aback quite a few times, until I realize what it is, is a bird(s) illuminated from below by city lights at night. It only works if the bird is just high enough that you can't make out its shape, but still low enough to be visible (dull orange from the sodium lights) and have a large angular velocity. (Around here, it's mostly owls: flying (fast!) at night, fairly large, and light-colored plumage.)

[JollyCrackers]

I think you left out one potential object: for instance, this past Friday night, June 6th, at about 10:30 PM PST looking toward the East I saw a rapidly descending bright light that was clearly not a meteor but most likely space junk (debris). 2014

[Chris Peterson]

I think you left out one potential object: for instance, this past Friday night, June 6th, at about 10:30 PM PST looking toward the East I saw a rapidly descending bright light that was clearly not a meteor but most likely space junk (debris). 2014

Why do you think it wasn't a meteor? Fireballs are almost always natural- falling space junk is rare in comparison. From a single vantage, it can be very hard to distinguish the two. The best way is by speed- space junk falls much slower, but that is usually only obvious when you see it passing high in the sky. Otherwise, perspective effects make it nearly impossible to determine true speed.

Most people will go their entire life never seeing reentering space debris.

[Yoduh]

and for aircraft, the US airforce has its own handy identification chart.

[Big Bad Bill]

The first time I thought I saw a flying saucer in the dark Texas skys, it was traveling very fast across the sky and reversing it direction and path. After a few of these gyrations, I realized it was a light on a lanyard attached to a weather baloon released from the meterological station on the base where I was stationed.

[anbium]

I once saw a bright comet high in the sky, no tail, but certainly with a fuzzy outline. Then Jupiter appeared where the comet had been. A faint wisp of cloud made the difference. (The comet was more exciting.)

[freeluna]

Definitely needs UFO sitings.

"Why?" you ask.

"Well, why not?"

Also should include the flying spaghetti monster and superman, just in case.

[Nitpicker]

I was taught as a child that planets don't twinkle. It seems to be a common belief, almost a superstition. Since taking up astronomy as a hobby, I see twinkling planets (and stars) all the time. I prefer it when they don't twinkle.

It's still a good rule of thumb. Even under terrible seeing conditions (like I have under the jetstream here in Colorado) it is rare for a planet above 20 or 30 degrees altitude to twinkle anywhere near as much as a star. It only takes a few inch wide ray path through the atmosphere to significantly reduce or eliminate scintillation (which is why stars rarely twinkle when seen through binoculars).

When I've got a group outside under the stars, I explain where the scintillation comes from, and show them (if the right objects are present) how different planets and stars always appear if you look at them critically.

(Check out Jupiter in the evening sky right now- a brilliant evening "star", which even very low looks nothing like any of the bright stars around it, such as Procyon or Capella. They may all be twinkling, but there's an obvious qualitative difference between the planet and the stars. Obvious if you make the effort to actually observe, that is. Most people don't- most people outside forums like this, anyway. BTW, Mercury is visible now, as well. It's not bright enough, or contrasty enough against the light sky, to normally show twinkling, even right on the horizon.)

In my (more humid) sky, high jetstream velocities do not seem to correlate with twinkling stars and planets. I can observe almost no twinkling with my eyes, then set up my scope and observe planets that have a smeared (rather than wobbly) appearance, which does correlate with high jetstream velocities. Then, I can pick another time with low jetstream velocities and the stars are twinkling like crazy. Twinkling seems to be caused more by turbulence at lower altitudes. I have not studied this topic exhaustively, but I have read explanations which match my own observations.

I can generally pick the planets because I know where they are roughly in the sky at most times and I know their hues and brightness. But I don't think I'm very good at quantifying scintillation. Right at the moment, Jupiter has the same brightness as Sirius, both low in the West after sunset for me, and (if I'm not in my backyard) it is easy to confuse them in a humid sky, or through patchy cloud, or when constrained by trees such that only a small portion of the sky is visible.

[Chris Peterson]

In my (more humid) sky, high jetstream velocities do not seem to correlate with twinkling stars and planets. I can observe almost no twinkling with my eyes, then set up my scope and observe planets that have a smeared (rather than wobbly) appearance, which does correlate with high jetstream velocities. Then, I can pick another time with low jetstream velocities and the stars are twinkling like crazy. Twinkling seems to be caused more by turbulence at lower altitudes. I have not studied this topic exhaustively, but I have read explanations which match my own observations.

Yes. I've done quite a lot of work with active and adaptive optics, and there's no doubt that different atmospheric effects cause scintillation, some high (like my jetstream issues), and some low (ground effect issues, or wind around local hills and valleys).

[Nitpicker]

I might also add that Jupiter has been low in my sky since I developed an observational interest in astronomy, just a couple of years ago. (And Venus is rarely high at night and Mercury is rarely seen in a dark enough sky.) This could easily explain why I think I see planets twinkling more than most other people. Mars and Saturn are high for me at the moment. Mars is a no brainer to spot by its red colour. And I have also learnt to spot Saturn by its unique golden hue. So I must admit that I can't really say whether I've seen Mars and Saturn twinkle very much when high in the sky, as I haven't been looking out for it. The nights when I am most seriously observing these two, tend to be nights of very good seeing (negligible wind, high pressure and negligible jetstream) where nothing twinkles very much at all.

[Berniega]

Ironically, after viewing today's APOD and discussing it on Facebook with friends, on the way home tonight, I saw a beautiful fireball over Lawrenceville, GA. Bright white, it broke into smaller pieces before going dark. About 9:30 this evening.

[firstmagnitude]

This is not a picture, this is a graphic, but not a picture per se!

[flybynite]

"Star" should be "Star or Planet"
"Planet" should be "UFO"

[Nitpicker]

This is not a picture, this is a graphic, but not a picture per se!

Yawanna start calling it AGOD?

[Pierino]

After "Is anything blinking - yes" I suggest another fork: "Do you get kidnapped by aliens? - No = Aircraft, Yes = Flying saucer