Friday, March 27, 2015

A Shattering of Old Dark Matter Theories

Summary: Thanks to new data, further theories of the nature of dark matter have been smashed to pieces! Pardon me for being excited about leading theories being wrong but that only means that I may have a part to play in developing the correct theory. So what has changed?

It turns out dark matter really doesn't seem to interact with anything apart from gravity. It doesn't even interact with itself. The study was conducted my using the Hubble and Chandra to look at collisions of different galaxies and watch the dark matter. Well, it looked at the gravitational lensing since dark matter itself is essentially impossible to see.

In the way science should work, Dr. Massey explains that "if you want to figure out what something is made out of, you knock it, or you throw it across the room and see where the bits go." The surprising part was that unlike the stars that slide past each other and the gas clouds that come to a halt in these collisions, the dark matter "seems not to interact with anything at all." Rather like a ghost, it just glides through the other dark matter like it's no big deal. Since it doesn't even interact with itself, many prominent theories for what dark matter is has now fallen apart. Which means exciting new possibilities for the rest of us in the future. 

BBC News
Science Mag

Sunday, March 22, 2015

Rosetta's Comet is Slowing Down

Summary: Despite the rover not being turned on again, astronomers are still learning new things about the chosen comet. For instance, it's changing rotation speed. The comet takes approximately 12.4 hours to complete one rotation, only that rate seems to be slowing down by one second per day. It seems like a small change but that is big in astronomical terms. It is actually a faster rate of change than in September. Back then it was slowing down by 33 milliseconds per day. (And right there is a differential equation for those who are so inclined.)

Scientists know the reason for this. The comet 67P is becoming more active which means there are gas jets shooting out of the rock and serving as propulsion, much like a rocket, only in the opposite direction of rotation, thus slowing it down. The jets actually shoot out of the comet at 800 meters per second and extend a few kilometers off the surface.

Astronomers found this out thanks to Rosetta still being in orbit around the rock. In order to keep the satellite in the correct trajectory, the navigators were using a system of landmarks on the surface to keep track of position. Only the landmarks were coming into view at a different time than expected.

BBC News

Saturday, March 14, 2015

More Secret Oceans

Summary: Jupiter's moon Ganymede is the latest solar system body now thought to have a secret ocean lying beneath its icy crust. The evidence for this lies in the aurora produced by the moon's magnetosphere. The auroras are also influences by Jupiter, but not as much as scientists thought they should be. The presence of a salty ocean below the surface would counteract some if the effects of Jupiter and leave what we see now.

This new evidence means that we are past the point of ambiguity but not certain yet. We will know more when a probe in 2030 orbits the moon and finishes with a crash landing into the surface. 

BBC News

And Happy Pi Day!

Wednesday, January 28, 2015

Changing the Speed of Light

Summary: Scientists in Scotland have successfully altered the speed of light. Incredible in my humble opinion. To do this, they used a mask to alter the shape of a photon. This slowed the light down. Then the photon was released back into free space and raced against a photon of unaltered shape. Amazingly, the altered particle remained at the lower speed.

At this initial stage it is nothing more than a curiosity but it could have implications for astronomy. While it would not make a difference in small distances such as between Earth and the moon, if photons mutate shape in nature then our distances to far off stars and galaxies may not be as accurate as previously assumed.

BBC News

Astronomical Updates

Highest Quality image of Ceres:
Ceres, the 950-km wide dwarf planet has a new image that is clearer than ever before. The resolution beats that of Hubble's image of Ceres. The cool thing is the image quality can only improve as Dawn approaches.

BBC News

New Horizons setting it's sights on Pluto:
The New Horizons probe will be zooming by Pluto on July 14th of this year but before it reaches the planet, it must start taking images to calibrate it's instruments and check its trajectory. The first images, with Pluto only as a tiny speck, should be released this week. Researchers are hoping that this mission will reveal many surprises about Pluto including new moons and possible rings.

BBC News

Large Asteroid and it's Moon:
The asteroid 2004 BL 86 was seen with a moon as it passed relatively close to Earth. The asteroid itself is 325m wide and it's moon is 70m wide.

BBC News

Sunday, November 30, 2014

Using the Eye of Sauron to see Great Distances

Summary: Two of my geeky obsessions have overlapped at long last. And in an exciting way too. As we strive to learn more about the beginnings of our universe, astronomers need new ways to measure distances to distant galaxies. The galaxy NGC4151, nicknamed The Eye of Sauron, has provided that.
The method relies on measuring the size of the supermassive black holes found at the center of all big galaxies. These black holes swallow up a huge about of gas and end up spewing emissions back out to become an AGN. The hot dust becomes a ring around the black hole which the astronomers used for measuring distance. By measuring the time delay between the emission of light from very close to the black hole and the infrared emission of the dust ring, we are able to know the distance the light has had to travel from the black hole to the ring.
Knowing the physical size and the apparent size of the ring means astronomers have a new method of measuring distance with only a 10% uncertainty. Not the most precise method we have but it is one that can be easily applied to many other galaxies out there.


Thursday, November 27, 2014

Lonely Stars

Summary: Two missions in 2010 and 2012 saw a rocket launched for a ten minute look at the Extragalactic Background Light (EBL) from above the atmosphere. What is the EBL? Professor Jaime Bock of JPL puts it this way: "It's very faint - but basically the spaces between the stars and galaxies aren't dark. And this is the total light made by stars and galaxies during cosmic history."

Having two separate data collecting missions that looked at different area of the sky allows the scientists to rule out fluctuations due to dust within our solar system. Even with this precaution, there was still extra light. The team believes that based on the brightness and blueness of the EBL, it shows that stars exist outside of galaxies. There might even be just as many stars outside galaxies as inside; it's that bright.

Of course other astronomers are skeptical of this conclusion. They concede it may be possible but are leaving their minds open for new and different possibilities.

BBC News
Science Mag