Astronomers have turned up 19 new gravitationally lensed quasars using photographs from the Hubble Space Telescope and the Sloan Digital Sky Survey (SDSS). 8 of these are what are known as “Einstein’s Rings”, where a nearby galaxy and a more distant quasar are perfectly lined up from our vantage point. The nearby galaxy acts as a lens to gravitationally focus the light from the quasar to magnify our view of it.
Astronomers have used the National Science Foundation’s continent-wide Very Long Baseline Array (VLBA), to peer deeper into the heart of the Milky Way than ever before. This image brings astronomers tantalizingly close the supermassive black hole believed to lurk there called Sagittarius A*. The strong pull of this black hole should create a distinctive shadow on the surrounding material, which should be visible if astronomers can double the sensitivity of this instrument.
What is the nature of the mysterious dark energy which is accelerating expansion of the Universe? In a recent study published in the Physical Review Letters, physicists are proposing two scenarios: thawing and freezing. In thawing, the expansion of the Universe should eventually come to a stop, and maybe even reverse. In “freezing”, the acceleration should continue indefinitely. A new mission: the Joint Dark Energy Mission (JDEM) has been proposed by NASA and the US Department of Energy, and should be able to determine which of these two scenarios is correct.
Wormholes are a mainstay in science fiction, providing our heroes with a quick and easy way to instantly travel around the Universe. Enter a wormhole near the Earth and you come out on the other side of the galaxy. Even though science fiction made them popular, wormholes had their origins in science – distorting spacetime like this was theoretically possible. But according to Dr. Stephen Hsu from the University of Oregon building a wormhole is probably impossible.
Wormholes are a mainstay in science fiction, providing our heroes with a quick and easy way to instantly travel around the Universe. Enter a wormhole near the Earth and you come out on the other side of the galaxy. Even though science fiction made them popular, wormholes had their origins in science – distorting spacetime …
Greetings, fellow SkyWatchers! The week might begin with a full Moon, but we’ll have plenty to explore as we learn about the anti-twilight arch and the “Belt of Venus”. We’ll watch as the Moon occults Antares, locate globular clusters, visit the planets and pinpoint asteroids. The weekend brings early dark skies along with challenges for all observers, so get ready to grab a comet by the tail, because…
Here’s what’s up!
Just before matter is gobbled up by a hungry black hole, it’s hurtling around the monster at nearly the speed of light. This heats up the material and it can release a tremendous amount of energy as X-rays. Different elements release energy with a specific fingerprint that astronomers can detect. Researchers from Europe have measured iron as it hurtles around black holes and found a relativistic effect because it’s moving so quickly. The team averaged out the X-ray light from 100 distant black holes to show the telltale signature of material about to be consumed by a black hole.
Astronomers from the Institute of Astronomy (IoA) in Cambridge, England have watched a bundle of matter at the heart of a galaxy 100 million light-years away as it orbited a supermassive black hole four times on its way to being destroyed. The material was approximately the same distance as our Earth is from the Sun, but instead of taking a year, it only took a quarter of a day, because of the massive gravity of the black hole. By tracking the matter’s doomed orbit, astronomers were then able to calculate the mass of the black hole: between 10 and 50 million solar masses.
The Gravity Probe B spacecraft, which is designed to test two predictions of Einstein’s General Theory of Relativity, has been scheduled to launch on April 17. The spacecraft will use four precise gyroscopes to determine how space and time are distorted by the gravity of the Earth and its rotation. The spacecraft will orbit the Earth once every 90 minutes, and gather data for more than a year, comparing any drift in its gyroscopes to the position of a guide star.
Astronomers have found several examples of galaxies which bend and focus the light from a more distant object, like a quasar. These are called gravitational lenses and they can reveal details that would just be a smudge to the most powerful telescopes. A recently discovered lensing galaxy called PMN J1632-0033 is unusual because the light from a distant quasar passes so close to the heart of the galaxy that the focused image can reveal information about the supermassive black hole in PMN J1632-0033.