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We residents of the Milky Way should have a little extra skip in our step today. Turns out our home galaxy is much bigger and moving a lot faster than we previously thought. That’s what researchers from the Harvard–Smithsonian Center for Astrophysics reported January 5th at the meeting of the American Astronomical Society.
Older studies of our galaxy’s structure and motion used indirect measurements. But we can now use radio telescopes to directly observe certain features of the galaxy when we’re in very different places in our orbit around the sun. And using traditional surveying methods, such as triangulation, researchers came up with the new figures.
First, we’re moving about 600,000 miles per hour in our galactic orbit, a lot zippier than the old estimate of 500,000. And the Milky Way’s total mass is about half again as much as we used to think. Which means we’re about as massive as the nearby Andromeda Galaxy. The Milky Way’s bigger mass does mean a greater chance of a gravity-driven collision with Andromeda. But if that clash occurs, at least now we’re in the same weight-class.
—Steve Mirsky
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10 Comments
Add CommentYOU could not help yourself? Same Weight class? What is that, zero for zero gravity? And should I schedule my arrival in Andromeda soon?
Reply | Report Abuse | Link to thisSame Weight class? You could not help yourself right? Weight is zero right? By the way, that intersection with Andromeda, should I cancel lunch?
Reply | Report Abuse | Link to thiswho is this guy frank stein and why does he comment twice, oops three times
Reply | Report Abuse | Link to thisAs the relative motions of Andromeda and the Milky Way have yet to be determined with any real certainty it is far too premature to be assuming a collision between the galaxies.
Reply | Report Abuse | Link to thisMost people seem to be using the older projections that we are moving directly toward each other but as this current study suggests, measuring motion in 3 dimensions is notoriously difficult to achieve and that the results from a 3 dimensional study can dramatically change everything - a 50% bigger galaxy is no small change!
Problem is that the further away something is the more difficult it is to determine 3 dimensional reality. Thus the current estimates of the speed the two galaxies approach each other can only reveal the component of the movement that is toward us. It cannot show the motion on any other axis and until that is determined accurately we cannot determine the actual direction Andromeda is traveling in and thus the likelihood of a collision, near miss or other scenario. There was some suggestion earlier in the year that the actual courses of the two galaxies would not collide but much more work needs to be done to confirm that, if true.
Meanwhile, if our Milky Way could speak, it might protest that predictions of its imminent demise are greatly exaggerated.
Reply | Report Abuse | Link to thisTo determine the axis of our galaxy
the half-mtass was
not known? Nevertheless I found another method with glaciers to specify
the rotation-axis of our galaxy.
Reference:
"the Milky Ways total mass is about half again as much"
To determine the axis of our galaxy
Reply | Report Abuse | Link to thistheir half-mass
was not specified a few years ago and actually not known.
This article is much better written than the AP article which contains the phrase "...denser, with 50 percent more mass, which is like weight." Can you believe it? See http://hosted.ap.org/dynamic/stories/S/SCI_MILKY_WAY?SITE=ORLAG&SECTION=HOME&TEMPLATE=DEFAULT
Reply | Report Abuse | Link to thisBy the way, I liked the joke about "weight class".
So... No Social Security checks after all?
Reply | Report Abuse | Link to thisHas anyone told Obama yet?
So does moving at 600,000 miles an hour in space enough speed to prevent us from being sucked into the massive black hole at the center of our galaxy?
Reply | Report Abuse | Link to thisAt 600,000 miles per hour, it would take the sun about 28,500 years or so to cross the 25.3 light years distance to Vega (provided it did not move during that time), which is roughly where the sun is aiming. So far the Sun has been travelling 4.6 billion years, completing about 23 nearly circular orbits around the galactic center (26,000 light-years away) without hitting anything big, or being sucked-in.
Reply | Report Abuse | Link to thisIf you are really looking for things to worry about, at a distance of 2 million light-years, maybe Andromeda is not our biggest concern, apparently, the Milky Way has been actively merging for some time with a dwarf galaxy found in the direction of Virgo, 30,000 light-years away and which is throwing 100,000 stars at us.
Maybe the more pressing danger is our own insanity. Knowing what we can do, perhaps it would be wiser to cancel your lunch after all.