Science I saw a shooting star tonight; as it burnt up in the atmosphere, it became a brilliant green. I have seen only yellow and white ones before. What causes the green color? Or could I have seen space junk burn up?
Exotic Objects If all the known matter in the universe were compressed into one colossal black hole, how big would it be (both size and mass)?
Science How difficult is it to launch an artificial satellite into a circular orbit versus an elliptical one? Is the final altitude of the orbit a key factor?
Exotic Objects, Science, Stars Astronomers making good time: Correcting for rotational instabilities of pulsars, the most precise clocks in the universe
Solar System Ask Astro web extra: What is the difference between a “cubewano,” “plutino,” and “Kuiper Belt object”?
