One Universe at a Time

The Pleiades (pictured below) is an open cluster that is easily seen in the night sky as a group of six (sometimes seven) stars in the constellation of Taurus.  It mostly contains bright blue (B-type) stars, and is about 440 light years away.  Or about 380 light years.  Or perhaps somewhere in between. 

If you’ve ever played on a seesaw with a small child, you know that you have to sit very close to the balance point (fulcrum) if you want to counterbalance the child.  This is because you are much heavier than the child.  A seesaw is a simple example of a concept known as center of mass.  The center of mass …

M101 ULX-1 is an ultra-luminous x-ray source in the Pinwheel galaxy (also known as M101).  As you can see in the image above, while it is quite bright at x-ray sources, it is not nearly as bright at visible and infrared wavelengths.  For this reason it was suspected that ULX-1 might be an intermediate mass black hole. 

If you’ve been following comet ISON, you’ve likely heard reports of its destruction, of its survival, fragmentation, etc.  So what’s really going on?  The short answer is that we’re still trying to find out. The challenge comes from the fact that ISON is a sungrazing comet.  That means its orbit takes it extremely close to the Sun at perihelion (closest …

In 1972, Carl Sagan, Linda Salzman Sagan and Frank Drake proposed a method of using pulsars to identify the location of Earth in the galaxy.  An image produced by their method was used on the plaque sent with the Pioneer probes.  The same image was used on the Voyager probe’s golden record. The basic idea is to indicate the distance …

One of the challenges with space telescopes is making sure they stay in proper alignment.  In order to take long exposures of stars and such, you must keep a telescope pointed in the same direction for long periods of time.  With ground-based telescopes you can mount them to the ground, and use tracking motors to account for the Earth’s rotation. …

There has been mention in the press of the discovery of a rapidly rotating supermassive black hole.  It turns out that this is not a recent discovery, but rather we’ve recently been able to prove (rather than strongly suspect) that this particular supermassive black hole is rapidly rotating.  The work was published in Nature (doi:10.1038/nature11938). Many supermassive black holes are …

While perhaps most famous for its now demoted status as a planet, Pluto is perhaps most interesting because of its system of moons.  Together with its largest moon Charon, it is sometimes referred to as a double planet.  Charon is by far Pluto’s largest moon, with a mass that is nearly 12% that of Pluto itself.  The other four moons …

You might be familiar with the star Betelgeuse.  It is a red giant star that marks the shoulder of the constellation Orion.  The Herschel Space Observatory took an image of Betelgeuse and its surroundings in the near infrared, and the results were recently published in Astronomy & Astrophysics.