APOD: The Large Cloud of Magellan (2010 Oct 16)

[neufer]

I don't think that our galaxy from the LMC would look all that different than it does from here, in terms of brightness.

The main difference would be the shape of the galaxy, and the sort of structure that would be apparent.

I think it would be noticeably brighter near the center
though I do agree that the main difference would be it's awesome structure.

It would be comparable to a near earth great comet of magnitude -2
(i.e., 6 times the brightness of Hyakutake at maximum brightness).

It would dominate the sky in a spectacular fashion.

Hyakutake on the evening of its closest approach to Earth

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<<Hyakutake became visible to the naked eye in early March 1996. By March 24, the comet was one of the brightest objects in the night sky, and its tail stretched 35 degrees. The comet had a notably bluish-green colour. The closest approach occurred on 25 March. Hyakutake was moving so rapidly across the night sky that its movement could be detected against the stars in just a few minutes. Observers estimated its magnitude as around 0, and tail lengths of up to 80 degrees were reported. Its coma, now close to the zenith for observers at mid-northern latitudes, appeared approximately 1.5 to 2 degrees across.>>

[Chris Peterson]

It would be comparable to a near earth great comet of magnitude -2
(i.e., 6 times the brightness of Hyakutake at maximum brightness).

No, it wouldn't. That's a measure of integrated brightness. The Milky Way has the same surface brightness as most any similar spiral galaxy, 20-22 magnitudes per square arcsecond. You would not see anything like a concentrated magnitude -2 area when viewing the Milky Way from the LMC.

The estimate for Hyakutake is also based on its extended size. I saw it under extremely dark skies, and it was impressive for its size (the tail crossed the sky), but not for its brightness. It could barely be seen at all except from dark sites; magnitude 0 stars, however, can be seen from the brightest cities.

[neufer]

It would be comparable to a near earth great comet of magnitude -2
(i.e., 6 times the brightness of Hyakutake at maximum brightness).

No, it wouldn't. That's a measure of integrated brightness. The Milky Way has the same surface brightness as most any similar spiral galaxy, 20-22 magnitudes per square arcsecond. You would not see anything like a concentrated magnitude -2 area when viewing the Milky Way from the LMC.

The estimate for Hyakutake is also based on its extended size. I saw it under extremely dark skies, and it was impressive for its size (the tail crossed the sky), but not for its brightness. It could barely be seen at all except from dark sites; magnitude 0 stars, however, can be seen from the brightest cities.

The pertinent question is: Did it dominate the night sky or not

If it dominated the night sky then it was, by definition, spectacular.

(You don't think they have extremely dark skies in the LMC?)

[Chris Peterson]

The pertinent question is: Did it dominate the night sky or not :?:
If it dominated the night sky then it was, by definition, spectacular.

I don't think I'd say it dominated the sky. In a sense it did, but only because it was so unusual. In absolute terms, it was less impressive than the Milky Way, and less obvious. It was spectacular for what it was; if it was a fixed feature of the sky, there every night, I don't think I'd be calling it spectacular at all.

[BMAONE23]

That makes sense. One of the properties of light in space is diffusion such that the farther you are from the light source, the fainter the source appears to become. For example by the time that the light from the sun reaches Pluto, it is only between 200 and 250 times brighter than the full moon or about 1/1600th as bright as on earth.
It is reasonable to presume that the Milky Way, although its angular size would be dramatically larger than Andromeda, would appear slightly less bright than it does in our own sky, about as bright as the magellanic clouds appear to our unaided eye

[Chris Peterson]

That makes sense. One of the properties of light in space is diffusion such that the farther you are from the light source, the fainter the source appears to become. For example by the time that the light from the sun reaches Pluto, it is only between 200 and 250 times brighter than the full moon or about 1/1600th as bright as on earth.
It is reasonable to presume that the Milky Way, although its angular size would be dramatically larger than Andromeda, would appear slightly less bright than it does in our own sky, about as bright as the magellanic clouds appear to our unaided eye

Surface brightness doesn't change with distance for extended objects (or with magnification). Imagine some little area of the Milky Way, which appears to have a certain brightness. If you get twice as far from it, the amount of light is reduced by a factor of four, but the area of the patch is also reduced by a factor of four. So the intensity per unit area is unchanged.

Under skies dark enough to see the Milky Way, you can also see the Andromeda galaxy. They both look about the same brightness- not surprising, as they are similar objects.

[KoolKatHebert]

Is anyone aware of an image created (and provide a link) to show what the Milky Way galaxy might look like from the vantage point of the Magellenic Clouds? Thanks!