Originally posted by LoveisanArt
Originally posted by ngchunter
Originally posted by Ophiuchus 13
But how can Hubble see other galaxies further away???
Galaxies are much brighter objects, and even the very far and faint galaxies Hubble observes involves exposures that are very, very long. Planetary
observations from hubble don't normally involve exposures that long for if they did the planet itself would tend to drown out the signal.
And not see them atleast near Pluto. This is somehting that makes 1 wonder?
That's not how it works. Very small objects like the moons of Pluto are very hard to detect.
What doesnt make sense to me in your reply - galaxies are not much brighter at all guy, they are so ridiculously far that the light emmiting from
those neighbooring (and not so neighbooring) galaxies would take literally forever to get through our gas clouds, different planets-moons-astroid
belts-stars and finally to the Hubblle..long exposure my ass How much light gets through the VIOD space between galaxies? We shouldnt even be
talking about other galaxies because physics and understandings on EA*rth ( ) do not exist the same in other galaxies.
Actually, yes. Galaxies can be brighter than Pluto, and appear larger in the sky that Pluto.
Let us take a look at Pluto
Diameter: 1,153 km
Apparent Magnitude: 13.65 to 16.3
Magnitude is the brightness of an object. The more positive the number, the fainter the light. For example, Venus can have an apparent Magnitude of
-4.9 to -3.8 which is very bright. A full moon can have an Apparent Magnitude of -12.4.
The brightest Pluto gets is +13.65. That's dim. Very, very dim. One of my telescopes is a 5 inch reflector. But it's not big enough to see Pluto.
It's just too dim for a 5 inch mirror to collect the light for my eyes. I would need an 12 inch or bigger reflector to see it with my eyes. I might
be able to capture it on my camera since I can expose it longer than my eyes with a smaller scope, but it will appear as only a small point of light
because it's so small.
Now let's talk about the Andromeda Galaxy
Size: it's around 120,000 light years across.
Apparent Size: 190' x 60' (how many degrees, minutes or seconds it covers the sky)
Apparent Magnitude: 3.44
It's a lot brighter than Pluto. So bright, that you can actually see it with your naked eyes. If you look at it's RA and Dec coordinates (it's next
to the constellation Andromeda), you'll see a faint smudge of light, as long as you are in a dark place with no city lights and no moon out.
Not bad for something that is about 2.5 million light years away. So even though it is much, much, much farther away than Pluto, it is also very, very
large, has somewhere around 200 to 400 billion stars in it, so yes, it's mcuh more visible and brighter than Pluto.
How about the Whirlpool Galaxy, M51a
Apparent Size: 11.2' x 6.9'
Apparent Magnitude: 8.4
Distance: 23 million light years
Here is a galaxy that is 10 times the distance of the Andromeda Galaxy, yet you can see it using only binoculars .
You can't see Pluto even with binoculars. Way too small and faint.
So you can go on and on about NASA all you want, but many of us have our own equipment and know quite well that it's much easier to photograph a
galaxy than it is Pluto. Do a Google search of Amateur Astrophotography, and look for pictures people have posted.
People really crack me up when they use Hubble and claim that it should be able to see things that it can't. Remember that Pluto is so small and
reflects so little light (the sun looks like a bright star you would see at night if you were on Pluto looking up at it), that there is not much for
Hubble to see. Where as a galaxy is HUGE, and emitting light, not reflecting it.