by Ann » Sun Sep 09, 2012 5:40 am
This is a beautiful and spectacular image that deservedly makes a comeback on this Sunday. Sundays are, after all, the "repeat day" of APOD.
I have a question about one of the many interesting links. The
"light years" link takes us to a Chandra page that says that the Hubble constant, the rate at which the (local) universe is expanding, is around 60 km/s/Mpc. I thought that the currently accepted value was more like 70 km/s/Mpc.
By the way, the same Chandra link suggests that the expansion of the universe is constant:
According to Hubble's law, the universe is expanding in such a way that distant galaxies are receding from one another with a speed which is proportional to their distance.
One of the most fascinating problems of modern cosmology is that the universe doesn't appear to be expanding at a constant rate, but instead it is accelerating.
Ann
This is a beautiful and spectacular image that deservedly makes a comeback on this Sunday. Sundays are, after all, the "repeat day" of APOD.
I have a question about one of the many interesting links. The [url=http://chandra.harvard.edu/photo/cosmic_distance.html]"light years" link[/url] takes us to a Chandra page that says that the Hubble constant, the rate at which the (local) universe is expanding, is around 60 km/s/Mpc. I thought that the currently accepted value was more like 70 km/s/Mpc.
By the way, the same Chandra link suggests that the expansion of the universe is constant:
[quote]According to Hubble's law, the universe is expanding in such a way that distant galaxies are receding from one another with a speed which is proportional to their distance.[/quote]
One of the most fascinating problems of modern cosmology is that the universe doesn't appear to be expanding at a constant rate, but instead it is accelerating.
Ann