Is Andromeda Drifting Towards Us?

In a Universe that’s expanding apart, isn’t it strange that Andromeda is actually drifting towards us? Dr. Thad Szabo from Cerritos College explains why this is happening.

“I’m Thad Szabo, and I teach astronomy and physics at Cerritos College.”

Is Andromeda drifting towards us?

“The reason that we see Andromeda moving toward us is because it’s nearby enough, and the Milky Way is massive enough and Andromeda is massive enough that they’re gravity is strong enough that there is not enough space between them that the space was able to expand and push them apart against the force of gravity. So if you take the Milky Way, all of its stars and all of its gas and dust, all of its dark matter, you’re looking at something that’s a trillion times the mass of the sun. You have the same for Andromeda, and they’re less than a mega parsec apart – to Andromeda, its about 2.2 billion light years. And so with that distance and that much mass, that’s close enough that gravity is drawing them together. Most galaxies, because they’re so distant, you do see them moving away due to the expansion of the universe.”

“But actually M81, which is about 12 million light years away, is also moving towards the Milky Way. It’s the most distant galaxy that doesn’t show red shift. So there’s enough gravity in this local group – I guess the local group is typically the Milky Way galaxy, the Andromeda galaxy, the Triangulum galaxy, and however many tens of dwarf galaxies that we’ve either discovered or haven’t discovered yet. But there’s also a bubble of about ten to twenty major size galaxies extending out to about fifteen million light years or so, and that’s kind of right on the border between where the expansion of the universe would drive things apart and where the gravity is strong enough to hold things together.”

Virtual Star Party – February 23, 2014 – Nebulae, Sunspots, and Planet “X”?!?

Hosts: Fraser Cain & Scott Lewis
Astronomers: David Dickinson, Gary Gonella, James McGee, Mike Simmons, Roy Salisbury, Shahrin Ahmad, Tom Nathe

Tonight’s views:
Jupiter with a nice view of the red spot, Venus approaching zenith, Bubble Nebula, the Pleiades, Orion Nebula, Horsehead Nebula, Flame Nebula, Running Man Nebula, the Moon, the Sun, the ISS (photo), the Rosette Nebula, Orion again, M33, Sunspots, Rosette again, California Nebula (multiple views), M81 & M82, Planet “X” (?!?), Andromeda, Flame Nebula again

We hold the Virtual Star Party every Sunday night as a live Google+ Hangout on Air. We begin the show when it gets dark on the West Coast. If you want to get a notification, make sure you circle the Virtual Star Party on Google+. You can watch on our YouTube channel or here on Universe Today.

Virtual Star Party – February 16, 2014: Fighting Crime while Transiting Jupiter!

Hosts: Fraser Cain & Scott Lewis

Astronomers: David Dickinson, Gary Gonella, James McGee, Tom Nathe, Mike Phillips, Mike Simmons, Roy Salisbury, Shahrin Ahmad

Views tonight: Horsehead Nebula, Flame Nebula, Europa Transit of Jupiter with Great Red Spot, a cluster of sunspots, Rosette Nebula, a near-Earth asteroid, a capture of Barnard’s Loop, Orion Nebula, M81, various telescopes of the astronomers, our moon, another transit of Jupiter by one of the moons, M67, NGC 2169-the “37” Cluster, our moon – full view, California Nebula.

We hold the Virtual Star Party every Sunday night as a live Google+ Hangout on Air. We begin the show when it gets dark on the West Coast. If you want to get a notification, make sure you circle the Virtual Star Party on Google+. You can watch on our YouTube channel or here on Universe Today.