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Space

Submission + - Earth could collide with other planets

Smivs writes: "The BBC are reporting an article in Nature magazine in which Astronomers calculate there is a tiny chance that Mars or Venus could collide with Earth — though it would not happen for at least a billion years. The finding comes from simulations to show how orbits of planets might evolve billions of years into the future. But the calculated chances of such events occurring are tiny. Writing in the journal Nature, a team led by Jacques Laskar shows there is also a chance Mercury could strike Venus and merge into a larger planet. Professor Laskar of the Paris Observatory and his colleagues also report that Mars might experience a close encounter with Jupiter — whose massive gravity could hurl the Red Planet out of our Solar System."
Space

Submission + - Junior-Sized Supernova Discovered by New York Teen (spacefellowship.com)

Matt_dk writes: "In November 2008, Caroline Moore, a 14-year-old student from upstate New York, discovered a supernova in a nearby galaxy, making her the youngest person ever to do so. Additional observations determined that the object, called SN 2008ha, is a new type of stellar explosion, 1000 times more powerful than a nova but 1000 times less powerful than a supernova. Astronomers say that it may be the weakest supernova ever seen."

Comment So their measurement of the Hubble constant is 69 (Score 1) 102

According to the article "the astronomers determined that the galaxy UGC 3789 is 160 million light-years from Earth". This translates to 49 Mpc. According to NED, the velocity (in the Cosmic Microwave Background frame) is 3385 km/s.

Therefore this measurement of the Hubble parameter is then 3385/49 = 69 km/s/Mpc.

(Unfortunately the article does not quote an uncertainty on the 49 Mpc measurement. Because of peculiar velocities, I would estimate that there is at least a 300 km/s uncertainty on the 3385 km/s velocity. )

Comment Re:What? (Score 1) 163

MoND does a good job of explaining rotation curves of spiral galaxies, but that's about it. It fails on the scales of clusters of galaxies, as even its proponents acknowledge. Nor does it make useful predictions for the growth of large-scale structure.

I have no idea what you mean when you say it explains the same things as the "String Hypothesis."

Comment Re:coloured dots!!! (Score 2, Interesting) 128

"9,000 ordinary supernovae" = 9000 x 10^44 Joules =~ 10^48 Joules.

According to Wikipedia, 1 ton (do they mean tonne) of TNT = 4 x 10^9 Joules, so this makes 2 x 10^38 tons of TNT equivalent.

And the largest bomb ever exploded is 5x10^8 tons of TNT.

So this would be ~ 10^30 of those, or around a million Yotta-bombs.

Not sure if that helps.

Comment Re:I haven't read the paper, but... (Score 4, Interesting) 285

Actually the orbital velocity is (surprisingly) close to constant, as in most spiral galaxies. In fact, it is these "flat" (i.e. constant as a function of galactocentric radius) rotation curves that were some of the earliest evidence for dark matter.

That having been said, my guess is that the velocities quoted in the press release refer to the Sun's (or more accurately the Local Standard of Rest's) velocity around the Galactic center.

Couldn't find the paper on arxiv.org ...

 

Education

Submission + - Real Open Source Applications for Education?

openeducation writes: I have been researching open source solutions for K-12 education pretty heavily for the past year and have been disappointed to find no real alternatives to the large administrative applications like student information systems, data warehouse, ERP, etc. But recently, I ran across Open Solutions for Education. http://os4ed.com/ This group appears to be making a serious effort at creating a stack of applications that are open source alternatives to the large and costly commercial alternatives. Centre, an open source student information system that has been around for awhile, is part of the solution stack. http://www.miller-group.net/ They have a data warehouse and are proposing an open source SIF alternative and an assessment solution. While the proof is in the pudding, these guys have working demos and they look pretty good for a first run. K-12 education in dire financial straits and solutions like these could help with lower TCO. Plus, education is a collaborative industry already, which makes perfect sense for open source.

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