Seashells, tornados and spiral galaxies all feature similar spiral shapes. Patterns repeat themselves in nature over and over again.

Gravity produces more abstract patterns: in much the same way that moving boats produce waves on water, moving stars can create gravitational waves in the fabric of space-time. Both types of waves lose energy as they move farther away from their source. Unfortunately, gravitational waves are very hard to measure by the time they reach Earth, and to this point, astronomers have not managed to detect gravitational waves from anywhere in the Universe.

But that doesn’t mean astronomers have given up. The quest to detect these waves has inspired scientists to figure out all kinds of ways gravitational waves might be created…

Discovered three short years ago, “monster” stars have masses between 200 and 300 times that of our sun—vastly larger than any other stars. Astronomers hoped that collisions between their supermassive remnants would produce measurable gravitational waves. At the 10th Edoardo Amaldi Conference on Gravitational Waves, Dr. Krzysztof Belczyński of the Astronomical Observatory of the Faculty of Physics at the University of Warsaw revealed his most recent findings.

Stars frequently form binary systems (two orbit around each other). Components of such systems collide once one object’s atmosphere takes over the other in a “common-envelope event.” The end result produces gamma-ray bursts accompanied by gravitational waves.

It would seem that a monster binary system would produce monster gravitational waves that even our current detectors could measure. Unfortunately, it seems that these monster stars will never get close enough to collide in the first place.

“In a supermassive binary star system, the situation is different,” says Dr. Belczyński. “We know that the components of such a system must be formed at a relatively large distance from each other. We also know that supermassive stars do not expand, so there cannot be a common envelope phase. This means that there is no physical mechanism that would effectively cause the orbit to tighten!”

“We stand practically no chance of detecting the gravitational waves from such a collision in the heavens. Unless…” Dr. Daniel Holz of the University of Chicago trails off in mid-sentence. We might detect such a collision if our current model of binary systems is wrong, which would demand a revision in our understanding of how the Universe works.

Thus the search continues for possible sources of gravitational waves—particularly of sufficient strength for us to detect. And preferably without the need to turn physics on its head.

Image: NASA

Every time an asteroid comes close to Earth, we learn something new about our Universe. With its closest approach last week, we learned that asteroid 1998 QE2 has its own moon.

Astronomers use close approaches by asteroids to take pictures and measurements that tell us more about space objects. On the scale of the solar system, apparently 3.6 million miles (about 15 times the distance between Earth and the Moon) is considered a “close approach.” Close-approach studies depend on the 70-meter Deep Space Network (DSN) antenna in Goldstone, California, with additional imagery supplied from other antennas in the DSN to maximize information content.

At this distance, the DSN was able to resolve a moon orbiting around asteroid 1998 QE2. As such, it is classified as a binary asteroid.  According to NASA, over 15% of asteroids travel in groups, where two or three objects orbit around one another.

The detailed study of asteroid 1998 QE2 marks a milestone in NASA’s Near Earth Object Program. “It’s one of the initial successes of our effort to find the big asteroids that could hit the Earth and cause global catastrophe,” said Paul Chodas, a scientist who is part of the Program.

The asteroid is not dangerous or threatening to earth, but astronomers can nonetheless use its close approach and that of others as valuable learning opportunities.

“Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features, and what they can tell us about its origin. We will also use new radar measurements of the asteroid’s distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise,” said Lance Benner, the principal investigator for the Goldstone radar observations at the Jet Propulsion Laboratory in Pasadena, California.

The more asteroids we catalog, the safer we are from a potentially dangerous impact. See our video on the B612’s Sentinel Mission for more information.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA/JPL-Caltech/GSSR