astronomical measurement... degrees??

[icebergahed]

Im trying to understand the relative size of deep size objects incomparison to the moon which i think is 1 degree. I know they vary but how big are they visually. for example the realm of galaxies near the leo constelation?

[E621Keith]

The size of DSO like galaxy and glob depends on your telescope and your sky condition. A small scope in light polluted sky will not show fainter details and the objects will appears much smaller. Often only the core of a galaxy is visible while the disk is too faint to detect.

The moon is a about 0.5 degrees wide. M31 is six times bigger with an apparent width of 3 degrees, but the large disk is faint and difficult to see in light polluted sky. Often you can only see the core.

The Leo triplets are around 10 arc minutes across

[NGC 1502]

Im trying to understand the relative size of deep size objects incomparison to the moon which i think is 1 degree. I know they vary but how big are they visually. for example the realm of galaxies near the leo constelation?

I expect you mean the apparent size of objects rather than the actual size, for example, the Sun and the Moon have an apparent size of about half a degree, even though their actual size is of course very different.

Markarians chain, a very nice curving arc of galaxies in Virgo, spans an apparent 2 degrees, Veil Nebula and M31 both around 3 degrees.

As said above, how much of M31 that can be seen varies according to telescope and sky conditions. I can recall showing M31 and nearby M32 to someone. He was puzzled as to why there was a large gap between the two, when in images he'd seen M32 was 'within' M31. The answer was that we could only see M31's brighter core, not the fainter outer parts.

Regards, Ed.

[Moonshane]

Another thing to bear in mind is

One degree = 60 arc minutes (3600 arc seconds)

One arc minute = 60 arc seconds

Every hour the apparent movement of objects across the sky is 15 degrees (360 divided by 24) or 900 arc minutes or 54,000 arc seconds

This http://coolcosmos.ipac.caltech.edu/cosmic_classroom/cosmic_reference/angular.html

gives a good summary, especially the use of fists at arms' length etc to guage distances.