Despite all the wonderful color images we have from the Hubble space telescope, there is no color camera on the Hubble. The main reason for this is scientific. When observing astronomical objects, you’d like to get as much light as you can from the object. You also want to get as wide a range of wavelengths as you can.
Rumor Weed
Yesterday there was a flurry of news about a gamma ray burst (GRB) appearing in the Andromeda galaxy. This would make it the closest observed gamma ray burst, which would be a boon for astronomers. News of this discovery travelled fast, particularly on Twitter and other social networks. Pretty soon a few news sites had picked up the story. But it turns out it wasn’t a gamma ray burst.
Color Kin
We generally think of asteroids as looking like gray rocks. While that’s true to our limited eyes, more sensitive instruments find they have a variety of colors. You can see an example of this in the image above of the asteroid Vesta. This false color image was made by observing Vesta at various wavelengths in the visible and infrared spectrum. It shows that Vesta has variations in color too subtle for us to see with our eyes.
Adaptation
If you’ve ever looked up in the night sky you’ve seen the twinkling of the stars. This twinkle is not due to the stars themselves, but to the turbulent motion of the Earth’s atmosphere. As starlight enters our atmosphere, the variations in density in turbulent air cause the light wave fronts to distort. So instead of reaching the telescope evenly like even rows of a band on parade, the wave fronts come in uneven and wobbly. This wobbly behavior is why stars appear to twinkle.
Losing Direction
Launched in 2009, Kepler was intended as a “planet hunter” telescope. It finds planets by observing stars for long periods of time. To make long observations, Kepler needs to be able to point in the same direction very precisely, and it must be able to adjust its direction if it starts to drift. So how do you keep a telescope oriented?
Reading the Rainbow
Our eyes see color through cones in our retina, where the three different types (S, M, and L) each have a slightly different range of wavelengths to which they are light sensitive. Through the response of these different cones our brains are able to distinguish different wavelengths of light, which we interpret as color. Telescope detectors typically have a much wider range of light sensitivity, which is good if you want to detect a great deal of light, but not so good if you want to observe a particular color range. So many telescopes have filters that block light outside a particular range.
Measuring the Sun
Last month there was an annular eclipse, but unless you happen to live in Antarctica, you probably didn’t get a chance to see it. You can, however make your own solar observation to measure the size of the Sun. This experiment uses the principle of parallax, and all you need is a sunny window, some cardboard, a pencil, and a tape measure.
Star Light, Star Bright
The Sun is a star like many others. It is special to us because it provides Earth with light and heat, but on a cosmic scale our Sun is an average, rather smallish star. How we came to understand this fact is a story with origins in the ancient past.
1776
[av_video src=’http://youtu.be/Nw_KfDEypTY’ format=’16-9′ width=’16’ height=’9′] As of this writing there are 1,776 known exoplanets. They are distributed in 1082 planetary systems. In this video, all of the exoplanetary systems are presented to scale, in a simulated flyby. The systems are also organized by date of confirmation, so you can see how planetary discovery really took off in recent years. Exoplanet …