APOD: Polaris and Comet Lovejoy (2015 Jun 02)

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APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by APOD Robot » Tue Jun 02, 2015 4:09 am

Image Polaris and Comet Lovejoy

Explanation: One of these two bright sky objects is moving. On the right is the famous star Polaris. Although only the 45th brightest star in the sky, Polaris is famous for appearing stationary. Once you find it, it will always appear in the same direction -- all night and all day -- for the rest of your life. This is because the northern spin pole of the Earth -- called the North Celestial Pole -- points near Polaris. On the left, about ten million times closer, is Comet Lovejoy, which noticeably changes its sky position by the hour. The featured image was taken last week. Officially designated C/2014 Q2 (Lovejoy), this disintegrating snowball is on a visit from the outer Solar System and will only appear near the North Star for a few more weeks. That should be long enough, however, for northerners with binoculars or a small telescope to see the greenish coma of this fleeting newcomer, perhaps with the help of a good star map.

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Ann
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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by Ann » Tue Jun 02, 2015 4:45 am

APOD Robot wrote:
One of these two bright sky objects is moving.
Actually both are moving. Polaris is moving too, like any other star in the sky. It is just too far away for us to notice during our brief lifetimes. But of course, Polaris is so close to the North Celestial Pole that it appears to be stationary.

Polaris is surrounded by a large bluish halo in this image. I have seen the same phenomenon in a few other Polaris pictures, although most images don't show it. There is quite a lot of nebulosity in the apparent vicinity of Polaris - apparent, because I don't know if the nebulosity is located at the same distance from us as Polaris. But if it is, could this blue mist be some sort of reflection nebula?

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by alter-ego » Tue Jun 02, 2015 5:21 am

Very nice. With the faint sky detail visible I couldn't help but try and successfully find the closest galaxies to Polaris. Polarissima Borealis is a pair of faint orangish-colored galaxies < 1°from Polaris. I don't know if Rogelio attempted to include them or they are bonus captures, but they are located not far above the "o" in Andreo. They also go by NGC 3172 (~14.5 mag) and a fainter, smaller neighbor MCG+15-1-10 about 2 arcminutes away.

Edit: Also worth noting is this image nicely shows the Milky Way's galactic glow lighting up the Integrated Flux Nebula IFN
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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by starsurfer » Tue Jun 02, 2015 7:30 am

Ann wrote:
APOD Robot wrote:
One of these two bright sky objects is moving.
Polaris is surrounded by a large bluish halo in this image. I have seen the same phenomenon in a few other Polaris pictures, although most images don't show it. There is quite a lot of nebulosity in the apparent vicinity of Polaris - apparent, because I don't know if the nebulosity is located at the same distance from us as Polaris. But if it is, could this blue mist be some sort of reflection nebula?

Ann
The blue halo is a photographic artifact caused by the intense brightness of the star. The nebulosity in the region are high latitude dust clouds that are illuminated by the entire glow of the Milky Way! There is also similar nebulosity near the south celestial pole.

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by henrystar » Tue Jun 02, 2015 10:17 am

Ann wrote:
APOD Robot wrote:
One of these two bright sky objects is moving.
Actually both are moving. Polaris is moving too, like any other star in the sky. It is just too far away for us to notice during our brief lifetimes. But of course, Polaris is so close to the North Celestial Pole that it appears to be stationary.

Polaris is surrounded by a large bluish halo in this image. I have seen the same phenomenon in a few other Polaris pictures, although most images don't show it. There is quite a lot of nebulosity in the apparent vicinity of Polaris - apparent, because I don't know if the nebulosity is located at the same distance from us as Polaris. But if it is, could this blue mist be some sort of reflection nebula?

Ann
Both are moving, indeed. I remember our tiny son looking out the car window and saying "the Moon is following us, Daddy!"

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by Craine » Tue Jun 02, 2015 12:26 pm

I never realized it was so dusty in that direction.
Which makes me wonder how far away the Galactic north is from our own Earths geographic North?
I always kinda assumed that in the direction of Galactic north and south the number of stars and dust would diminish significantly.

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by Ann » Tue Jun 02, 2015 12:38 pm

The plane of the Solar system is tilted in relation to the plane of the Milky Way.

So Polaris is far away from the galactic north pole.

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by Craine » Tue Jun 02, 2015 1:04 pm

Ann wrote:Source: http://www.scienceminusdetails.com/2012 ... eways.html The plane of the Solar system is tilted in relation to the plane of the Milky Way.

So Polaris is far away from the galactic north pole.
Ann
Wow! I figured the solar system would be somewhat tilted vs. the galactic plane. But I never realized it was that much.

Thanx Ann.

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by illexsquid » Tue Jun 02, 2015 7:17 pm

Each equatorial plane is perpendicular to its respective axis. So you know that the plane of the galaxy is at a huge angle to the ecliptic, if you've ever seen the plane of the galaxy traverse the sky in a more-or-less north-south direction on summer evenings. I always resented that the galactic center was so low on the horizon for me at my northerly latitude. Those southerners get all the good stuff.

Oh, and thanks for identifying the skyfuzz. For me, the nebulosity is the most interesting and surprising thing about this detailed, sharp image.

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by Boomer12k » Tue Jun 02, 2015 9:29 pm

Another dusty corner of the sky to sweep... the work just keeps piling up....

If you look at the other stars, they are also surrounded by the Camera Artifact "aura"....

Very nice picture.

I hope when the comet recedes, the World will be a better place...

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Re: APOD: Polaris and Comet Lovejoy (2015 Jun 02)

Post by Nitpicker » Wed Jun 03, 2015 2:38 am

If you look at Polaris on a Galactic Coordinate grid, you can see that it is only ~26.5&deg; north of the Galactic Equator (labelled Galactic Plane, which is almost but not quite the same thing):
polaris_vs_galaxy.PNG
And of course, the Celestial pole (Earth's axis of rotation, which currently points to Polaris in the North) is inclined to the Ecliptic pole (effectively the Solar System's axis of rotation) by ~23.5&deg;. And the Celestial pole maintains this inclination fairly well, as it precesses (rotates) about the Ecliptic pole once every ~26,000 years.

The Solar System's axis is inclined at ~60&deg; to the Galaxy's axis and I think this stays comparatively constant over many precession cycles. The Earth's axis is currently inclined at ~63.5&deg; to the Galaxy's axis. Around the year 8400 CE, the Earth's axis will be inclined at its maximum of ~83.5&deg; to the Galaxy's axis. And another 13,000 years after that, the Earth's axis will be inclined at its minimum of ~36.5&deg; to the Galaxy's axis.
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