Expert: Tom Whiting - 5/9/2011

Question
Q1: Has anyone been inside another galaxy in history?
Q2: Would any other galaxies be like our Milky way?
Q3: How many galaxies are there ?
Q4: How many days would it take to get to the closest galaxy to the milky way?
Q5: Would it be possible, if anytime that the Milky way were to be swallowed by a black hole?
Q6: Has anything alien-inhabited been found i nthe Milky Way?
Q7:There are several galaxies; Spiral,Barred Spiral, elliptical, and irreagular, are there any others?

Answer
Hi Alison,
1. NO. We haven't even been to the nearest star, Alpha Centauri, in our own Galaxy, at only 4.3 light years distant.
2. Yes, there are many spiral galaxies... but old elliptical galaxies are more common than spiral galaxies.
3. We don't know the exact number, but as Carl Sagan used to say, "billions and billions and billions" of galaxies.
4. The closest galaxies to the Milky Way (not counting the small dwarf galaxies that the Milky Way is currently cannibalizing) are our two companion Magellanic Clouds (Large and Small) in the Southern Hemisphere, at an estimated distance of about 160,000 light years. So at the speed of light, which is of course impossible to achieve, it would take 160,000 Earth years to get there.
So if you want that number in days, multiply 365 days by 160,000 years... at light speed.

5. No.  There is actually a super-massive black hole at the center of the Milky Way... it can "swallow" (better to say rip apart and accrete) some of the nearby stars in the center, say out to about 50 light years, but since the entire Milky Way is some 100,000 light years in diameter, it's totally impossible for all the estimated 200-400 billion stars in the Milky Way to "fall into" that black hole. We are quite safe at an orbital distance of some 30,000 light years from the central black hole.  So don't lose any sleep over it.
6. No... not yet.
7. Yes, the one category you missed is the dwarf galaxies... but most of those are classified as either irregular or elliptical.  Also there are far more than just "several" galaxies,... as stated above, there are billions and billions of them.
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA

FOLLOW UP:
Galaxies are the most common deep sky object that we view through our telescopes (as compared to globular star clusters, open star clusters, planetary nebulae, and emission nebulae and all other nebulae). Some famous examples of galaxies you can punch up to view are the Whirlpool Galaxy (M-51), the Black Eye Galaxy (M-64), the Andromeda Galaxy (M-31), the Sombrero Galaxy (M-104), the sunflower galaxy (M-63), and all those ellipticals in the Virgo Supercluster out there 65 million light years - M's 84, 86, 87... over 1000 galaxies just in the Virgo Supercluster.
Some other of my favorites are M-81, M-82, M-100, NGC 4565 and NGC 891... you can punch those up too.
Tom