APOD: The Tidal Tail of NGC 3628 (2012 Jul 06)

[geckzilla]

There's nothing wrong with a little bit of healthy criticism. More errors used to get fixed before APODs got published but it's just been slipping through the cracks lately. Just keep posting any found mistakes here (but please don't call anyone names in the process) and they usually get fixed before the next day.

[smitty]

Just keep posting any found mistakes here (but please don't call anyone names in the process) and they usually get fixed before the next day.

Except in this case it still has not been fixed, more than a day later. It still says "up and to the left" on the main apod website. Not an earthshaking problem in the grand scheme of things perhaps, but it's always good to get things as right as possible, even a day or more after the fact. People do go back and look at archives, after all.

[Guest]

Can you imagine the night-sky from a planet orbiting a star in the tidal tail? Being above the galactic plane and outside of the galaxy, but so close...

It would look similar to the Milky Way in our own sky, but less impressive, since it wouldn't go from horizon to horizon.

I don't think you thought that through. To us the Milky Way is a band because we're inside it and therefore very close to the galactic plane. The stars in the tail are outside the body of the galaxy and not in line with the galactic plane. I'm imagining M31 (Andromeda Galaxy) but stretching across most of the sky with the tail forming a faint link to the horizon.

[Chris Peterson]

Can you imagine the night-sky from a planet orbiting a star in the tidal tail? Being above the galactic plane and outside of the galaxy, but so close...

It would look similar to the Milky Way in our own sky, but less impressive, since it wouldn't go from horizon to horizon.

I don't think you thought that through. To us the Milky Way is a band because we're inside it and therefore very close to the galactic plane. The stars in the tail are outside the body of the galaxy and not in line with the galactic plane. I'm imagining M31 (Andromeda Galaxy) but stretching across most of the sky with the tail forming a faint link to the horizon.

The stars in the tail wouldn't show up at all (in the sense of showing any discernible structure- the nearby ones would simply be stars in the sky). But the nearby parent galaxy would show up as a linear structure in the sky very similar to the Milky Way, since it appears the tail is roughly on the same plane as the galaxy. If the view were down onto the galaxy, the night sky would probably be less impressive- lots of stars, but not much structure- something like the Milky Way spread out over a big piece of the sky.

[geckzilla]

Do you think even the brightest galaxy would be much more noticeable than the Milky Way's band? Like, maybe a big, bright elliptical without all the dust would actually be a relatively bright circular glow in the night sky. Like a constant night light if you are in the right hemisphere.

[Chris Peterson]

Do you think even the brightest galaxy would be much more noticeable than the Milky Way's band? Like, maybe a big, bright elliptical without all the dust would actually be a relatively bright circular glow in the night sky. Like a constant night light if you are in the right hemisphere.

Yeah, I think if you were near a low dust elliptical or spiral galaxy it would probably be brighter, maybe by several times. The thing is, we're much more sensitive to contrast than to absolute brightness, so even a bright, big diffuse glow might not be very impressive- something like light pollution, maybe. I think the view from the tail in this picture would show the parent galaxy edge-on, which would be somewhat dimmer because of dust in the galaxy plane (as with the Milky Way), but the distinct linear glow with well defined edges would probably be a lot more eye catching.