APOD: How to Identify that Light in the Sky (2021 Nov 14)

[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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[jks]

Hi,

Presently (at least in my browsers), the date appears at the lower left of the image, rather than above the image.

[Starski2]

"Are any astronauts waving at you?"
Yes:"Are they human?"
Yes: "International Space Station
No: "E.T.s"

[RocketRon]

"Are your retinas burning".

No, but the candle is.
If you've ever seen any festival of lights or similar, all those mini-'hot air balloons' can be a puzzle.
Especially just one or 2, drifting along.

https://content.presspage.com/uploads/6 ... angmai.jpg

(* - potentially a serious fire hazard in some parts)

[Ann]

Thanks, I really like it!

As for the ISS, I think I have seen it twice, but I noticed that it moved, it was very bright, and then quite quickly it got fainter and disappeared.

I had to laugh at the Norwegian translation of the chart. Norwegian sounds like a funny version of Swedish to us Swedes, and we find it both funny-weird and funny-ha ha. So, "Is it moving? So quickly you almost missed it?" was translated into Norwegian as "Flytter det på seg? Kjemperaskt?"

That is funny, but I can't explain it to anyone who isn't familiar with the Scandinavian languages. Anyway, "kjempe" as an intensifier of "raskt" (=fast) is really funny, and "raskt" is rather funny in itself too. It sounds so enthusiastic in a very Norwegian way!

Click to play embedded YouTube video.

Ann

[Newtownian]

Probably been said before but this taxonomy manages to omit most of the really interesting naked eye fuzzy objects, depending on sky darkness - 4 galaxies (LMC, SMC, Andromeda, Triangulum), 7 (caldwell) + 10 (messier) fuzzy globular clusters brighter than magnitude 7, a number of fuzzy naked eye nebulae (e.g. Sagitarius and Orion) and spectacular but also fuzzyish open clusters (e.g. Pleiades and the Behive).

Oh and places where there is no light.....coal sack nebula, various dust clouds in the Milky Way.....and the centre of the galaxy itself.

[Kenttor]

Except that Venus is not even close to the sun at this time. In Brisbane it is high in the sky at sunset. Edit: off topic, but my best viewing of the ISS was just afte the shuttle had cast off, they were close but distinct and very bright.

[Astronymus]

Is the object gone after the explosion?
Yes: Meteor
No: Impactor
Do you hear a thud near you?
Yes: Meteorite for your collection
No: Mass Extinction Event

[orin stepanek]

Inquisitive puppies!

I remember this APOD; got my attention! A nice nirage!

And you decide what it is in a moment!

[APOD JJ]

How about lightning, sprites, and auroras?

[rmercer]

Torn between thinking "UFO" should be included, and relieved that it was not!
Of couse APOD is thoroghly professional, but it is likely true that some sporadic "lights in the sky" originating in the atmosphere are not identified.

[Chris Peterson]

Torn between thinking "UFO" should be included, and relieved that it was not! :roll:
Of couse APOD is thoroghly professional, but it is likely true that some sporadic "lights in the sky" originating in the atmosphere are not identified.

They're all UFOs until your path through the chart terminates!

[Dave92F1]

Satellites often (usually!) "blink", just slowly (as they rotate).

I suggest changing "International Space Station" to just "Space Station". There are presently 2 (ISS, Chinese) and will soon enough be others. For the same reason, I suggest changing "astronauts" to "people".

[Chris Peterson]

Satellites often (usually!) "blink", just slowly (as they rotate).

Satellites occasionally blink in this way. Rarely, though. Tumbling satellites represent only a fraction of all the satellites we can see crossing the sky.

[E Fish]

Torn between thinking "UFO" should be included, and relieved that it was not!
Of couse APOD is thoroghly professional, but it is likely true that some sporadic "lights in the sky" originating in the atmosphere are not identified.

They're all UFOs until your path through the chart terminates!

Exactly! Since the U simply means unidentified. Interesting that it's become synonymous with aliens.

[Fred the Cat]

You might see one of these or get hit by an unidentified falling object

[neufer]

Sunao Tsuboi, Hiroshima survivor who campaigned against nuclear war, dies at 96
By Emily Langer, Washington Post, November 5, 2021

<<Sunao Tsuboi, an engineering student at a university in Hiroshima, was making his way across the city’s Miyuki Bridge en route to a morning class when, in a sudden, terrifying moment on Aug. 6, 1945, blazing light flooded his surroundings. A blast threw him more than 30 feet, leaving him unconscious. When he awoke, the light was gone, subsumed by an awful pall. “I know now,” he told the British Daily Mirror decades later, “I was under the mushroom cloud.”

Convinced of his own impending death, Mr. Tsuboi used a pebble to scrawl the words “Tsuboi died here,” a marker for friends who might come searching for his remains. When he died Oct. 24 at 96, he had outlived by more than 76 years his expectation that day, when the world first observed the horror of nuclear war and when Mr. Tsuboi was set on his path as an international advocate for disarmament.>>

[dprovan]

Torn between thinking "UFO" should be included, and relieved that it was not!
Of couse APOD is thoroghly professional, but it is likely true that some sporadic "lights in the sky" originating in the atmosphere are not identified.

They're all UFOs until your path through the chart terminates!

Of course, I immediately thought of UFOs, too. With the humor evident in the chart, I was kinda surprised that they weren't a terminal point. I wasn't disappointed by the omission, but I has to think about where they'd fit. At first, I was thinking along your lines, basically you could get to UFO anywhere that you didn't get to a terminal. That's certainly the logical answer. But then I decided the better approach to account for actual UFO enthusiasts would be a node at the very top, before considering any of the other questions: "Do you want this to be a UFO? Yes: UFO."

[Fred the Cat]

Sunao Tsuboi, Hiroshima survivor who campaigned against nuclear war, dies at 96
By Emily Langer, Washington Post, November 5, 2021

<<Sunao Tsuboi, an engineering student at a university in Hiroshima, was making his way across the city’s Miyuki Bridge en route to a morning class when, in a sudden, terrifying moment on Aug. 6, 1945, blazing light flooded his surroundings. A blast threw him more than 30 feet, leaving him unconscious. When he awoke, the light was gone, subsumed by an awful pall. “I know now,” he told the British Daily Mirror decades later, “I was under the mushroom cloud.”

Convinced of his own impending death, Mr. Tsuboi used a pebble to scrawl the words “Tsuboi died here,” a marker for friends who might come searching for his remains. When he died Oct. 24 at 96, he had outlived by more than 76 years his expectation that day, when the world first observed the horror of nuclear war and when Mr. Tsuboi was set on his path as an international advocate for disarmament.>>

If only Damascus Road had today's APOD as a sign?

[De58te]

They missed one light in the sky that falls under - Is it moving? so quick you almost missed it. Their answer states it is a fireball, but I was thinking of a lightning bolt. Those aren't really ball shaped and they aren't made out of fire. Made out of electricity, which scientifically isn't fire, but it can cause fire upon contact. You can also say there is a thunderous sound similar to an explosion so it also can't be a bolide.

[neufer]

They missed one light in the sky that falls under - Is it moving? so quick you almost missed it. Their answer states it is a fireball, but I was thinking of a lightning bolt. Those aren't really ball shaped and they aren't made out of fire. Made out of electricity, which scientifically isn't fire, but it can cause fire upon contact. You can also say there is a thunderous sound similar to an explosion so it also can't be a bolide.

Click to play embedded YouTube video.

<<Ball lightning is an unexplained phenomenon described as luminescent, spherical objects that vary from pea-sized to several meters in diameter. Julio Rubinstein, David Finkelstein, and James R. Powell proposed that ball lightning is a detached St. Elmo's fire (1964–1970). St. Elmo's fire arises when a sharp conductor, such as a ship's mast, amplifies the atmospheric electric field to breakdown. A free ball of ionized air can amplify the ambient field by its own conductivity. When this maintains the ionization, the ball is then a soliton in the flow of atmospheric electricity. A review of the available literature published in 1972 identified the properties of a "typical" ball lightning, whilst cautioning against over-reliance on eye-witness accounts:

• They frequently appear almost simultaneously with cloud-to-ground lightning discharge
  
  They are generally spherical or pear-shaped with fuzzy edges
  
  Their diameters range from 1–100 cm, most commonly 10–20 cm
  
  Their brightness corresponds to roughly that of a domestic lamp
  
  A wide range of colors has been observed, red, orange, and yellow being the most common
  
  The lifetime of each event is from one second to over a minute
  
  They tend to move at a few meters per second, most often in a horizontal direction, but may also move vertically, remain stationary, or wander erratically
  
  Many are described as having rotational motion
  
  It is rare that observers report the sensation of heat, although in some cases the disappearance of the ball is accompanied by the liberation of heat
  
  Some display an affinity for metal objects and may move along conductors such as wires or metal fences
  
  Some appear within buildings passing through closed doors and windows
  
  Some have appeared within metal aircraft and have entered and left without causing damage
  
  The disappearance of a ball is generally rapid and may be either silent or explosive
  
  Odors resembling ozone, burning sulfur, or nitrogen oxides are often reported

The emission spectrum of a natural ball lightning

---

In January 2014, scientists from Northwest Normal University in Lanzhou, China, published the results of recordings made in July 2012 of the optical spectrum of what was thought to be natural ball lightning made by chance during the study of ordinary cloud–ground lightning on the Tibetan Plateau. At a distance of 900 m, a total of 1.64 seconds of digital video of the ball lightning and its spectrum was made, from the formation of the ball lightning after the ordinary lightning struck the ground, up to the optical decay of the phenomenon. Additional video was recorded by a high-speed (3000 frames/sec) camera, which captured only the last 0.78 seconds of the event, due to its limited recording capacity. Both cameras were equipped with slitless spectrographs. The researchers detected emission lines of neutral atomic silicon, calcium, iron, nitrogen, and oxygen—in contrast with mainly ionized nitrogen emission lines in the spectrum of the parent lightning. The ball lightning traveled horizontally across the video frame at an average speed equivalent of 8.6 m/s. It had a diameter of 5 m and covered a distance of about 15 m within those 1.64 s.

Oscillations in the light intensity and in the oxygen and nitrogen emission at a frequency of 100 hertz, possibly caused by the electromagnetic field of the 50 Hz high-voltage power transmission line in the vicinity, were observed. From the spectrum, the temperature of the ball lightning was assessed as being lower than the temperature of the parent lightning (<15,000 to 30,000 K). The observed data are consistent with vaporization of soil as well as with ball lightning's sensitivity to electric fields.>>

[rwlott]

My first thought upon seeing today's APOD was that this is one of Randall Munroe's XKCD comics, as he often uses flowcharts to humorous effect. Here's an example: https://xkcd.com/1688/

[MarkBour]

As for the ISS, I think I have seen it twice, but I noticed that it moved, it was very bright, and then quite quickly it got fainter and disappeared.
. . .

Ann

I have enjoyed this: https://spotthestation.nasa.gov/
I wondered if this was only available in the United States, but when I put in "Malmo, SWE" as a location, it came up with data.

Mainly, this service allows you to get advanced warning of personalized sighting opportunities in an email (they send an email each day that conditions are right. They don't bother you on other days. Typically, in a month, I get about 2-3 emails).

On good days, I would describe the ISS in the sky as "a steady, stately, progression".

[Ann]

As for the ISS, I think I have seen it twice, but I noticed that it moved, it was very bright, and then quite quickly it got fainter and disappeared.
. . .

Ann

I have enjoyed this: https://spotthestation.nasa.gov/
I wondered if this was only available in the United States, but when I put in "Malmo, SWE" as a location, it came up with data.

Mainly, this service allows you to get advanced warning of personalized sighting opportunities in an email (they send an email each day that conditions are right. They don't bother you on other days. Typically, in a month, I get about 2-3 emails).

On good days, I would describe the ISS in the sky as "a steady, stately, progression".

Thanks, Mark! Of course, it will not be so useful in the winter, because the sky here is overcast 28 days out of 30. But when weather reports say we'll get a clear spell, it would be nice if the ISS paid me a visit!

Ann

[waterfeller]

Many years ago I watched a full moon rising in early evening. Suddenly, there was a bright white light about the size of bright Venus in the Moon's south east quadrant. After several seconds, my only thought was "OMG, they have nuked the Moon." I watched transfixed for 15-20 seconds as it got slightly brighter but no apparent motion relative to the Moon. Then it disappeared suddenly. After another 10-15 seconds I could just make out the silhouette of a light airplane moving slowly to the east. It must have been flying directly toward me with landing lights on before slightly altering course and turning off the lights.