Starship Asterisk*

by **johnnydeep** » Sun Jan 09, 2022 1:00 am

Ann wrote: ↑Sat Jan 08, 2022 9:20 am
De58te wrote: ↑Sat Jan 08, 2022 8:42 am Wow, today's APOD at first glance is so eerie. Those dark tripod things in the foreground reminded me of the H.G. Wells / Orson Welles movie "The War of the Worlds". The Martian tripods actually looked like that and one is even firing a ray gun blaster that just happens to look like a meteor shower. ( Correction, Orson Welles made the radio broadcast, not the movie.)
You're right! The largest-looking telescope in the APOD seems to be firing a ray gun blaster (although the lethal ray is only a Quadrantid)!

Ann

Actually, it’s taking a direct hit

by **neufer** » Sat Jan 08, 2022 3:56 pm

Chris Peterson wrote: ↑Sat Jan 08, 2022 2:39 pm
orin stepanek wrote: ↑Sat Jan 08, 2022 1:27 pm
Confusing why a constellation gets dropped?
Originally, the constellations were basically just asterisms and loosely defined areas around them. 100 years ago the constellations were formalized by rectilinear boundaries (that is, the constellations are not the asterisms anymore). And Quadrans simply didn't fit into the scheme, so it was dropped.

https://en.wikipedia.org/wiki/Constellation#88_modern_constellations wrote:

Click to play embedded YouTube video.
Out of the 88 modern constellations,
36 lie predominantly in the northern sky,
and the other 52 predominantly in the southern.

Out of the 88 keys on a typical piano,
36 are black, and the other 52 are white.

<<In 1922, Henry Norris Russell produced a general list of 88 constellations and some useful abbreviations for them. However, these constellations did not have clear borders between them. In 1928, the International Astronomical Union (IAU) formally accepted 88 modern constellations, with contiguous boundaries along vertical and horizontal lines of right ascension and declination developed by Eugene Delporte that, together, cover the entire celestial sphere; this list was finally published in 1930. The aim of this system is area-mapping, i.e. the division of the celestial sphere into contiguous fields. The boundaries developed by Delporte used data that originated back to epoch B1875.0, which was when Benjamin A. Gould first made his proposal to designate boundaries for the celestial sphere, a suggestion on which Delporte based his work. The consequence of this early date is that because of the precession of the equinoxes, the borders on a modern star map, such as epoch J2000, are already somewhat skewed and no longer perfectly vertical or horizontal. This effect will increase over the years and centuries to come.>>

by **Chris Peterson** » Sat Jan 08, 2022 2:39 pm

orin stepanek wrote: ↑Sat Jan 08, 2022 1:27 pm .jpg
Confusing why a constellation gets dropped? :shock:

Originally, the constellations were basically just asterisms and loosely defined areas around them. 100 years ago the constellations were formalized by rectilinear boundaries (that is, the constellations are not the asterisms anymore). And Quadrans simply didn't fit into the scheme, so it was dropped.

by **orin stepanek** » Sat Jan 08, 2022 1:27 pm

Confusing why a constellation gets dropped?

by **Guest** » Sat Jan 08, 2022 9:57 am

... "known to some as the Plough". This caused me much confusion, years ago. I'm British, so "The Plough". "The Big Dipper" sounded odd as the big dipper is a fairground ride, (a roller coaster), and when I tried to picture it as represented by the stars of the Plough, it didn't work very well. It was along time before I realised that in the US, a dipper is a scoop!

by **Ann** » Sat Jan 08, 2022 9:20 am

De58te wrote: ↑Sat Jan 08, 2022 8:42 am Wow, today's APOD at first glance is so eerie. Those dark tripod things in the foreground reminded me of the H.G. Wells / Orson Welles movie "The War of the Worlds". The Martian tripods actually looked like that and one is even firing a ray gun blaster that just happens to look like a meteor shower. ( Correction, Orson Welles made the radio broadcast, not the movie.)

You're right! The largest-looking telescope in the APOD seems to be firing a ray gun blaster (although the lethal ray is only a Quadrantid)!

Ann

by **De58te** » Sat Jan 08, 2022 8:42 am

Wow, today's APOD at first glance is so eerie. Those dark tripod things in the foreground reminded me of the H.G. Wells / Orson Welles movie "The War of the Worlds". The Martian tripods actually looked like that and one is even firing a ray gun blaster that just happens to look like a meteor shower. ( Correction, Orson Welles made the radio broadcast, not the movie.)

by **alter-ego** » Sat Jan 08, 2022 6:05 am

I observed this shower many years ago, mainly to experience its short duration (~6 hours). I was skeptical I'd be able to sense a peak within a 6-hour timeframe, but I was actually surprised I could. The peak was distinct enough that I quit observing about 4:00am after not seeing any reasonable counts. I got the impression the show was over.

by **Ann** » Sat Jan 08, 2022 6:03 am

Quadrantids of the North.
Image Credit & Copyright: Cheng Luo

Here are some of the stars that you can see in the APOD. Note that the Big Dipper is "upside down", or at least it seems to be oriented the other way when I see it in the sky!

What about Alkaid? Ah, I couldn't help myself. Note that Alkaid itself appears to be "shooting a Quadrantid" as if it was firing a gun!

Well, the thing is that Alkaid is one of my favorite stars, at the same time as it is a disappointment to me. It is fascinating because it is a star of spectral class B3 at a distance of only about a hundred light-years - that's nearby as early B-type stars go! But at the same time I'm disappointed, because it is not particularly blue as early B-type stars go, with a B-V of only −0.099, and it is not all that bright, only about 150 times solar in yellow-green light.

Oh well! I loved the fact that Alkaid seemed to be firing a Quadrantid! Alkaid, get your gun!

Ann

by **APOD Robot** » Sat Jan 08, 2022 5:05 am

Quadrantids of the North

Explanation: Named for a forgotten constellation, the Quadrantid Meteor Shower puts on an annual show for planet Earth's northern hemisphere skygazers. The shower's radiant on the sky lies within the old, astronomically obsolete constellation Quadrans Muralis. That location is not far from the Big Dipper, at the boundaries of the modern constellations Bootes and Draco. In fact north star Polaris is just below center in this frame and the Big Dipper asterism (known to some as the Plough) is above it, with the meteor shower radiant to the right. Pointing back toward the radiant, Quadrantid meteors streak through the night in the panoramic skyscape, a composite of images taken in the hours around the shower's peak on January 4, 2022. Arrayed in the foreground are radio telescopes of the Chinese Spectral Radioheliograph, Mingantu Observing Station, Inner Mongolia, China. A likely source of the dust stream that produces Quadrantid meteors was identified in 2003 as an asteroid.

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