APOD: How to Identify that Light in the Sky (2017 Sep 24)

[APOD Robot]

How to Identify that Light in the Sky

Explanation: What is that light in the sky? Perhaps one of humanity's more common questions, an answer may result from a few quick observations. For example -- is it moving or blinking? If so, and if you live near a city, the answer is typically an airplane, since planes are so numerous and so few stars and satellites are bright enough to be seen over the din of artificial city lights. If not, and if you live far from a city, that bright light is likely a planet such as Venus or Mars -- the former of which is constrained to appear near the horizon just before dawn or after dusk. Sometimes the low apparent motion of a distant airplane near the horizon makes it hard to tell from a bright planet, but even this can usually be discerned by the plane's motion over a few minutes. Still unsure? The featured chart gives a sometimes-humorous but mostly-accurate assessment. Dedicated sky enthusiasts will likely note -- and are encouraged to provide -- polite corrections.

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[Ann]

It made me smile. I find it funny.

Ann

[Rusty Brown in Cda]

Classic decision tree.
Speaking of celestial objects, the ISS is due to pass over my part of the world near Toronto at its most brilliant a couple of times next week before dawn. Worth getting out of bed for if skies are clear.
http://iss.astroviewer.net/observation.php

[Boomer12k]

Making 90 degree turns, stops, shoots straight off at super high speeds...goes straight up...and up, and up, and up, and keeps going up and NEVER CROSSES THE SKY until it is out of sight? Circles commercial airliners, nearly missing them, then shoots off at mach 15?

YES? Then it is "Swamp Gas".....riiiiiiiiiiiiiight.....

:---[===] *

[Javachip3]

Another light-emitting entity belongs in the decision tree. Years ago, while visiting Palm Springs, California, I was stargazing without optical aid around 3:00 AM and saw a very bright, steady, non-moving, non-blinking, non-twinkling point of light to the west, about 20 degrees above the horizon. It was about the right color and brightness for Venus, but Venus is never that far away from the Sun. The object did not move or change over several minutes of viewing. I trembled as I considered the possibility that I might be witnessing the brightest supernova in centuries. Finally I remembered that I was in Palm Springs, and realized that the supernova candidate had a terrestrial explanation: a light bulb on nearby Mount San Jacinto.

[Confused]

I once was hiking up the Pacific Crest Trail from the Mojave River Forks Reservoir to the hot springs and I thought I saw something flying very fast over the river. So the answer to the question "So quickly you almost missed it?" is yes, it was really going that fast. I don't know if they were testing because it is a relatively small passageway or if they wanted to take pictures of the naked people at the hot springs. I forgot to ask about it when I got to the hot springs, I should have.

[Quintin]

I liked this
I´d add under Planet, Easy to spot with the naked eye? Yes: Venus, Mars, Jupiter, Saturn; No: Mercury

Thanks !!
Quintin Gumucio
Enköping - Sweden

[Lukas Stratmann]

Fuzzy without tail: probably the Andromeda galaxy?

[Ann]

Click to view full size image

[JohnD]

That's ridiculous, Ann.

The Enterprise has artificial gravity on board, as any fule kno. No need to spin the accomodation.

John

[mister T]

I think they forgot "training exercise"

[Redbone]

I saw one that was a little different:
really big -> No
moving -> Yes
quickly -> No
blinking -> No
jumping around, left, right, up down -> Yes

It is a meteorite that is coming directly at you!

[Chris Peterson]

Pretty good. Officially, "bolide" and "fireball" are synonyms, so shouldn't have separate boxes. But colloquially the terms are often used this way, so for a light hearted chart, it works. Decaying space debris looks a lot like a fireball, just a bit slower than usual and often with more of a train. It's common enough that it should probably have its own box. And a big miss is the absence of balloons- everything from little mylar birthday balloons a few hundred meters away to weather balloons tens of kilometers away commonly show up and make people wonder what they're seeing.

[ta152h0]

I saw quiet helicopters late at night with their lights on. a flock of them, likean air show. It was misterious until the pakistani adventure was revealed.

[De58te]

Some lights I have seen which I am not sure where they fit in the chart. Can you identify them? (1) This is a fairly bright light, moves quickly, forms a long root like squiggly line, sometimes to the ground, is sometimes pictured being thrown by the mythological Zeus or Thor, and is usually accompanied by a loud thunderous sound a couple seconds later. (2) This light is rather silent, mostly dim, varies in color from greens to reds to whites, sometimes covers a large portion of the sky, and is usually seen above the Arctic Circle. (or below the Antarctic Circle.) (3) These lights are rather localized to a square mile or so. They are first seen as a thin sliver of light shooting almost vertically. Then there is a loud sound and a burst of multitudinous colors from a reds to blues and whites that usually spread out in a fan shape, ball shape, or a flame shape that lasts a few seconds and then they fade out. These lights seem to be not randomly seen but usually during sporting events finals, musical festivities and on the Fourth of July after dusk and at midnight of New Year's Eve.

[snooks5647@hotmail.com]

While living on Oahu a couple of decades back, in the middle of the night while in the bathroom, I witnessed a HUGE light coming from the West, going over the house (and island), and disappearing in the East. It happened almost instantaneously, made no noise, and lit up the entire sky. I figured it had to either be a meteor or space junk. No space junk is on the chart, and should have a place on it.

[Chris Peterson]

While living on Oahu a couple of decades back, in the middle of the night while in the bathroom, I witnessed a HUGE light coming from the West, going over the house (and island), and disappearing in the East. It happened almost instantaneously, made no noise, and lit up the entire sky. I figured it had to either be a meteor or space junk. No space junk is on the chart, and should have a place on it.

That would almost certainly have been a meteor. Space junk isn't that bright as a rule, and travels slower than the slowest meteors. If you're underneath a long space junk trail (e.g. horizon to horizon) the event will last from 30-60 seconds. A fireball of that length is likely to last less than 10 seconds.

[elchananj]

I've seen once a light in the sky, very bright, like a ball of fire, seemingly not moving, from afar high in the north sky. (ruled out venus)
after a minute Iv'e noticed it is moving slowly upwards, and then downwards, very slowly, I was very exited of the possibilities,
then it started smoking, and I realized it was an illuminating bomb...

[Mokurai]

Fuzzy without tail: probably the Andromeda galaxy?

Or one of the Magellanic Clouds, for those further south.

[BrentNZ]

One thing missing is Iridium Flares. Not sure whether they are "yes" or "no" to "so quickly you almost missed it ?". They're not that quick, but if you're looking at a different part of the sky and just catch it out of the corner of your eye, as you turn towards it, it can already be fading.

Also "is it blinking ?" "Yes" could be a tumbling rocket body.

[Dr_Steve]

Is it Christmas Eve, you see a lighted red nose and someone is shouting "Ho, ho, ho?"

[neufer]

Is it Christmas Eve, you see a lighted red nose and someone is shouting "Ho, ho, ho?"

That might be my grandfather: Rudolph Carl Neuendorffer.

(I'm still trying to figure out everything in my grandmother's thick Bryn Mawr Lamb calculus text.)

Bryn Mawr College Register of Alumnæ and Former Students:

• Sinn, Esther Marion,......875 West 180th Street, New York City.
  
  A.B., 1904, group, Latin and Mathematics.
  
  Married, 1917, Mr. Rudolph C. Neuendorffer. One son, one daughter.

[T Van K]

You neglected to include very large objects hovering in the sky with lights all over them: one type with very loud audible tones being repeated over and over, the other with destructive rays shooting out.

[fleetwood]

A number of years ago during a Lunar eclipse, I observed what appeared to be two satellites traveling in tandem. That caught my attention as that seemed not right, when one made a 90 degree turn in an instant and headed on that trajectory until fading out of sight quickly.

[D^3]

A quick reply to Quintin Gumucio: Under the right conditions, Mercury is actually quite bright! Earlier this month, when Mercury was near both Mars and the bright star Regulus, Mercury was the brightest of the three.