Since Galileo's first sky observation by telescope, we have learned many things hidden in the universe.
We learned that comets come from Oort's cloud. We could tell the exact number of galaxies in our group. We predicted the number of clusters in the universe. We even measured the limit of observable universe.
We have learned things lying at the edge of the universe, but we have not learned so much about something nearer, even the distance to our nearby galaxy is still not exactly known.
According to Jonathan Amos in "Key Galaxy Distance Re-measured", Grzegorz Pietrzynski from the Universidad de Concepción, Chile and his colleagues studied binary stars in Large Magellanic Cloud (LMC) Galaxy and managed to determine the distance of the galaxy,which plays the crucial role in astronomical study, to be 163,000 light-years.
The number is critically important owing to its use as a calibration to study stellar properties, matter distribution and especially to find Hubble's constant. Edwin Hubble found that a galaxy moves with a velocity proportioning to its distance, and Hubble's constant is non-negligible here.
By determining if there is any change in a value of Hubble's constant, we are able to find an evolution of the universe - static , forever expandable or collapsing universe.
However, to do so is not as easy as it sounds, due to its difficulty in measuring distances of faraway galaxies.
There are some useful methods to do that. For example, the method of standard candle which we assume that any supernova happening in any galaxy has a certain real luminosity, but its apparent luminosity will be much less because of extinction caused by interstellar matter. We measure the distance of LMC to build an extinction curve and finally be able to find the non-linear relation between an apparent magnitude of a supernova exploding in one galaxy and its distance, then, surely, we can actualize the model of our universe.
We also use LMC as a calibrator in other methods as well because it is a nearby galaxy and an effect on stellar extinction is small comparing to further galaxies. It is undeniable that its distance is very important for modern astronomical research.
I hope that this project will be completely expanded soon. And I also hope that "an ultra-precise map of more than a billion stars in and near the Milky Way" will be beyond our reach in only next few years.
Who knows, maybe next ten years kids will have their universe maps in their study room.
_________
Reference
Amos, J. (2013, March 8). Key galaxy distance re-measured. BBC News Magazine.
Retrieved March 10, 2013 from http://www.bbc.co.uk/news/science-environment-21692346
Like Ming, I think it amazing how the blobs of star dust in our skulls have reached a point where we can now learn so much about the vastness of the universe, yet there remains vastly more to learn.
ReplyDeleteI think that the money for this sort of research is very well spent, as is the very expensive LHC that might have uncovered the Higg's boson, confirming some of our deepest guesses about the universe at the most elementary level.
And then there are the wonders of our brains themselves. There are plenty of mysteries remaining to be unravelled there.