Archive for the ‘galaxy’ Tag

Our galaxy is 50% more massive than previously thought

Artist's conception of what the Milky Way looks like from above the galactic plane. Click to enlarge and see labels.

Artist's conception of what the Milky Way looks like from above the galactic plane. Click to enlarge and see labels.

Our galaxy, the Milky Way, appears to be about 50% more massive than we previously thought.  A team of scientists lead by Mark Reid of the Harvard-Smithsonian Center for Astrophysics have conducted a detailed 3-D survey of our galaxy and determined that it’s diameter is about 15% greater than previously believed and it is spinning more rapidly than had been thought.  The greater rotational speed indicates the presence of more mass, most of which is probably dark matter.

It is much harder to measure our own galaxy than those which are a million light years away because we’re embedded within it and can’t see the whole thing.

The Andromeda Galaxy, the most distant object you can see with your naked eye, will crash into our galaxy in about 2-3 billion years.

The Andromeda Galaxy, the most distant object you can see with your naked eye, will crash into our galaxy in about 2-3 billion years.

The new findings, which were presented today at the American Astronomical Society’s convention in Long Beach, California, mean that the Milky Way is about the same size as, not smaller than, our nearest large neighbor: the Andromeda Galaxy.  Andromeda, a.k.a. M31, may be larger in volume than our home galaxy, but appears to only be about the same mass, likely due to differing amounts of dark matter between the two bodies.

The new mass data has another implication for Milky Way-Andromeda relations: the anticipated collision between the two galaxies may now happen sooner than previously thought.  But don’t worry, it’s still 2-3 billion years in the future.  The Sun won’t go nova for about 5-6 billion years, so it will still be around, as will the Earth. However, the expansion of the Sun will make it impossible for liquid water to exist on the Earth’s surface in only one billion years.

The Mice Galaxies (so-called because of their appearance) are colliding and will likely form one larger galaxy, in many millions of years.

The Mice Galaxies (so-called because of their appearance) are colliding and will likely form one larger galaxy, in many millions of years.

Galaxies collide are hardly unique occurrences in the universe.  When they do happen, the stars themselves don’t collide, they’re too far apart for that to be likely; however, a star or star system might be ejected from it’s galaxy or, less likely, the orbits of planets within a star system might be disrupted.  In any event, the gravity of the two galaxies will rip them apart until, millions of years later, they may form a new, bigger galaxy.  It is thought that the Andromeda-Milky War collision will form a large elliptical galaxy, which some have preemptively dubbed Milkomeda.

While you’re waiting for the collision, note that 2009 is the International Year of Astronomy.  Learn more about our endlessly fascinating universe by checking out some of the above links, or research any astronomical topics which are of interest to you.  It’s your universe—learn about it!

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Something outside observable universe pulling galaxies

Cosmologists have discovered that 700 clusters of galaxies are being pulled by a massive gravity source that is outside the observable universe.

Since the universe is approximately 13.7 billion years old we can see no more than about 13.7 billion light years in any direction.  However, the entirety of the universe is larger—potentially unimaginably larger—than that due to an early expansionary phase in the universe in which space itself expanded at an incredible rate.  The mass that is pulling on those galaxy clusters, each of which is made up of many galaxies, lies beyond our event horizon, outside the observable universe.

Some of the researchers hypothesize that the mega mass in question is the result of an area of the universe that did not undergo as extensive a period of hyper inflation, leading to a more dense area of space.

In these regions, space-time might be very different, and likely doesn’t contain stars and galaxies (which only formed because of the particular density pattern of mass in our bubble).

It could include giant, massive structures much larger than anything in our own observable universe. These structures are what researchers suspect are tugging on the galaxy clusters, causing the dark flow.

“The structures responsible for this motion have been pushed so far away by inflation, I would guesstimate they may be hundreds of billions of light years away, that we cannot see even with the deepest telescopes because the light emitted there could not have reached us in the age of the universe,” Kashlinsky said in a telephone interview. “Most likely to create such a coherent flow they would have to be some very strange structures, maybe some warped space time. But this is just pure speculation.”

Needless to say, scientists are very surprised at this unexpected finding.