The morning sky will play host to a spectacular gathering of solar system objects grouped closely together tomorrow (Nov. 22), but it won't be easy for observers on Earth to see it.
The sun, moon, three planets and the dwarf planet Ceres will all appear within a 20-degree span of sky. (For reference, your clenched fist held up to the sky measures about 10 degrees across.) Mercury and Saturn will be just west of the sun and new moon, while Venus and Ceres will be to the east. Unfortunately, the bright sun will wash out the beautiful "conjunction," but interested observers can still use a planetarium software program like Starry Night to check out the stunning event.
The same phenomenon that causes a bumpy airplane ride, turbulence, may be the solution to a long-standing mystery about stars' birth, or the absence of it, according to a new study using data from NASA's Chandra X-ray Observatory.
Galaxy clusters are the largest objects in the universe, held together by gravity. These behemoths contain hundreds or thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees.
This hot gas, which is the heftiest component of the galaxy clusters aside from unseen dark matter, glows brightly in X-ray light detected by Chandra. Over time, the gas in the centers of these clusters should cool enough that stars form at prodigious rates. However, this is not what astronomers have observed in many galaxy clusters.