One of the aspects of astronomy that’s hard to wrap your head around is the immense time scales of the heavens. We measure the lifetimes of stars in billions of years, while the light from the nearest galaxies takes millions of years to reach us. Human civilization, on the other hand, is measured in thousands, and a human lifetime tens. …
A Galaxy Far, Far Away
A while back in Nature a paper was published on the most distant confirmed galaxy discovered so far. The paper is behind a paywall, but you can see the arxiv version here. The galaxy, known as z8 GND 5296 has a measured redshift of 7.51. You can see the galaxy in the image above. So just how far away is this galaxy? It depends on which distance you are talking about.
Foreshadowing
If you happen to catch this eclipse and are waiting for a total one, you won’t have to wait too long. Make plans for August 21, 2017. On that day a total eclipse will cross the US from Oregon to South Carolina, making it within a day’s drive of most of the country.
National Geographic Effect
You can see this effect in the image above. On the left is a Voyager II image of Jupiter’s great red spot as it appeared in NatGeo and elsewhere. On the right is the same image in its more true-color form. You can see why the colors were boosted. The true-color image lacks much of the depth and richness we like to see in images.
More Echoes
With the discussion of light echoes today, here’s another interesting one. In 2002 the star v838 Monocerotis swiftly brightened to about a million times the brightness of the Sun before dimming down again. This burst of light then traveled outward from the star, illuminating the gas and dust surrounding the star. Because the light burst was relatively short, this meant that successive layers of the gas and dust were illuminated as the sphere of light expanded.
Energy Bubble
Yesterday I talked about the Fermi gamma ray telescope, and how it allowed us to make much more precise observations of gamma rays in the universe. Part of the purpose of the Fermi telescope is to observe gamma ray bursts, but its broader purpose is to make a sky survey of gamma ray sources in the universe. Already it has found something quite interesting.
Star of Bethlehem
When stars are portrayed in media, they are often shown with long spikes emanating from them. Perhaps the most common example is that of the “star of Bethlehem” which, according to the story, led the wise men to baby Jesus. Of course when we look at stars in the night sky, we don’t see any such spikes. Stars twinkle due to atmospheric disturbances, but that’s about it. In photographs, however, bright stars often have such long spikes. So what causes them? It all has to do with an interesting bit of optics.
Two By Two
Yesterday I talked about the detection of gamma ray bursts, intense blasts of gamma rays that occasionally appear in distant galaxies. Gamma ray bursts were only detected when gamma ray satellites were put into orbit in the 1960s. This is because gamma rays are absorbed by our atmosphere. Even then, the detectors were relatively primitive and couldn’t determine the direction of the bursts. Instead, multiple satellites were used to triangulate the location of these bursts. Since then, gamma ray astronomy has gotten much more sophisticated.
Counting in the Dark
The Alpha Magnetic Spectrometer (AMS) is a particle detector located on the International Space Station. It’s designed to detect high energy particles known as cosmic rays, and a while back it made news regarding claims it had detected dark matter. It hadn’t, but instead had detected an excess of positrons that might be due to dark matter. It could also be due to other things, which is why claiming it had found evidence of dark matter was a bit disingenuous. Now the AMS is back with more data. Despite some claims, the new results don’t hint at dark matter any more than last time, but it is still solid work.