Starship Asterisk*

"Lovely blue comet, where do you roam?"

"Through the Hyades, weren't you paying attention?????"

:---[===] *

Once again, today's APOD is a lovely picture!

[float=left][img2]https://tinyurl.com/ya9ofcv2[/img2][c][size=85]Blue comet C/2016 R2 PanSTARRS.
APOD caption:
[quote][i]the head or coma of the comet appears with a slightly [b][color=#00BF00]greenish[/color][/b] hue[/i][/quote][/size][/c][/float] [float=right][img2]https://www.e-education.psu.edu/astro801/sites/www.e-education.psu.edu.astro801/files/image/Lesson%2011/q4_schur.jpg[/img2][size=85][c]Comet NEAT (Q4) by Chris Schur.
[url=https://apod.nasa.gov/apod/ap040512.html]APOD caption[/url]:
[quote][i]a [b][color=#0080FF]blue[/color][/b] coma surrounding the comet's nucleus[/i][/quote][/c][/size][/float]






















I marvel at the way a mostly blue coma is called "slightly greenish" in 2018, while an almost traffic-light green coma was called blue in 2004!

It is of course also interesting to compare the very blue comet C/2016 R2 PanSTARRS with the very "normal-colored" comet NEAT (Q4), with its greenish coma, yellowish dust tail and blue ion tail.

Anyway. Rogelio Bernal Andreo's image is delightful. Not only does it show off this remarkably blue comet very well, but it is also a great portrait of the Hyades. I wasn't aware of the fluffs and puffs of dark dust in the (apparent) vicinity of the Hyades. The darkest of them seems almost ready to hatch a tiny little Hyad-let! Well, probably not! Seeing star birth in progress in this cluster would be quite astonishing, since the age of the Hyades is estimated to be more than 600 million years.

I forgot to say that the color contrast between the comet and the stars in the Hyades cluster is extremely satisfying in today's APOD! :D

Ann

[quote="ta152h0"]maybe cop cars can have blue comets on the light bar ?[/quote]
Back in the 1960s quite a few black and white Comets had red lights on top.

maybe cop cars can have blue comets on the light bar ?

That's a really really lovely picture! Thanks, Rogelia Bernal Andreo! :D

Ann

[url=https://apod.nasa.gov/apod/ap180118.html][img]https://apod.nasa.gov/apod/calendar/S_180118.jpg[/img] [size=150]Blue Comet in the Hyades[/size][/url]

[b] Explanation: [/b] [url=https://apod.nasa.gov/apod/ap121224.html]Stars of the Hyades[/url] cluster are scattered through this mosaic spanning over 5 degrees on the sky toward the constellation Taurus. Presently cruising through the Solar System, the [url=https://apod.nasa.gov/apod/ap180112.html]remarkably blue comet[/url] C/2016 R2 PanSTARRS is placed in the wide field of view using image data from January 12. With the apex of the V-shape in the Hyades cluster positioned near the top center, [url=http://stars.astro.illinois.edu/sow/aldebaran.html]bright Aldebaran[/url], alpha star of Taurus, anchors the frame at the lower right. A cool red giant, Aldebaran is seen in orange hues in the colorful starfield. While the stars of the Hyades are gathered 151 light-years away, Aldebaran lies only 65 light-years distant and so is separate from the cluster stars. [url=https://theskylive.com/planetarium?obj=c2016r2&date=2018-01-12&h=00&m=00#ra|4.27708847383563|dec|17.798274448522356|fov|16]On January 12[/url], C/2016 R2 was over 17 light-minutes from planet Earth and nearly 24 light-minutes from the Sun. Its blue tinted tail largely due to [url=https://arxiv.org/abs/1801.01199]CO+ gas[/url] fluorescing in sunlight, the [url=https://solarsystem.nasa.gov/planets/comets/basic]head or coma[/url] of the comet appears with a slightly greenish hue, likely emission from diatomic carbon.

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