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Fraser
2003-Nov-04, 05:06 PM
SUMMARY: An international team of astronomers have discovered a new galaxy colliding with our own Milky Way. This new galaxy, Canis Major, is located only 42,000 light years away from the centre of the Milky Way - it's our new "closest galaxy". Canis Major was discovered during an infrared survey of the sky, which allowed the astronomers to peer through the obscuring dust and gas of the Milky Way. Canis Major is quite small (as galaxies go); it only contains about a billion stars.


Comments or questions about this story? Feel free to share your thoughts.

zephyr46
2003-Nov-04, 11:39 PM
This is a recent discovery coming on the back of the Sagittarius dwarf galaxy (http://www.astro.virginia.edu/~mfs4n/sgr/) article. The more you know, the more you know you don't know :)

Matthew
2003-Nov-05, 10:29 AM
We are also gobbling the galaxy up, at least the Milky Way is. :o

Canis Major will increase the Milky Way's mass by about 1%.

GSii
2003-Nov-05, 12:53 PM
Is this the reason why our planet was hit several times?
There is a small cycle of ~65 million year and a larger one of >200 million years - perhaps the time it takes for 1 cycle around our milky way?

IonDrive
2003-Nov-05, 10:55 PM
Originally posted by GSii@Nov 5 2003, 12:53 PM
Is this the reason why our planet was hit several times?
There is a small cycle of ~65 million year and a larger one of >200 million years - perhaps the time it takes for 1 cycle around our milky way?
I read several articles about mass extinctions and found that there were so many of them in Earth's history that actually one could argue for every cycle length over 20 million years, like 30, 35, 47, 58,... (insert number of choice :D )

Someone remember, for example, the big fuss about a supposed brown dwarf companion to Sun which was said to cause mass extinctions every 26 million years, the same time period it was supposed to circle the Sun once?
Actually I just made a small calculation which showed that the semimajor axis of such a long orbit would be significantly over 80.000 AU (slightly dependent on the object's mass), which is about 1.3 light years, which is not much less than a third of the distance between Sun and Alpha Centauri. So as this 26 million year orbit would have a very dim chance to remain stable for more than about 20 million years it's now wonder such an object was never found.

Note: While the extinction of the dinosaurs about 65 million years ago seems to have been caused by an asteroid impact, nearby supernovae have been discussed as a possible reason for several other mass extinctions. The sun requires approximately 220-225 million years for one revolution around the galactic core,
which means that about every 50-60 million years the sun crosses one of the four spiral arms, which contain the stars massive enough to explode as supernovae, so you might have actually made a good point, GSii.
But the term "nearby" here means distances lower than 50 lightyears (lower than 20, say other sources). Since the next star massive enough to go supernova according to what we know about the masses of giant stars is Beteigeuze in Orion, there is NO supernova candidate within a distance of 200 light years to the sun, which means that we are in no danger at all to suffer from these kind of event for at least a few million years to come. :)

Guest
2003-Nov-16, 04:36 PM
What about our 250 light year ocillatin up and down from the galaxy rotation plain as the earth and sun circle the center every 225m years?