Dear Urban Astronomer Thanks for all your interesting celestial tidbits, which my hubby and I enjoy very much. We are just viewers and treasurers of the skies we love so much, not a professional like you! Could you perhaps enlighten us about a very bright star which is currently to be seen approx 30% up from the horizon to the east. When we say to the east, it is where our sun sets during the winter season. The star … Continue reading →
As of February 2024, we know of sixteen moons orbiting Neptune. The largest, Triton, was discovered only 17 days after Neptune itself was found in 1846 and it would be over a hundred years before any others were first seen. Triton is one of the larger moons in the Solar System with a diameter of 2700km, and orbits backwards around Neptune. The most recently discovered moon, by contrast, is less than 8 km across. No doubt there are more … Continue reading →
As of 11 July 2012, we know of five moons around Pluto. The largest, Charon, was discovered in June 1978, and is closer to its parent in size than any other moon in the Solar System. In fact, when it was first discovered it was found that the combined mass of the two had thrown out all calculations of Pluto’s size. Up till then, Pluto was assumed to be much larger than we know it is today. The next two … Continue reading →
The Arietids meteor shower, as it’s name suggests, has its radiant in the constellation Aries. It lasts from late May till early July and peaks between the 7th and 8th of June. The meteoroids of this shower enter the atmosphere at speeds of about 38 kilometers per second, and are usually “earthgrazers”, meaning we see them hitting the atmosphere at a shallow angle, ploughing slowly right across the sky. But most interestingly of all, the Arietids are a daylight shower. … Continue reading →
When a star runs out of fuel to burn, it’s outer layers get ejected into space and it’s core collapses under gravity into a white dwarf. If the star was really big, more than about 8 times the mass of our Sun, then it continues to collapse, becoming denser and denser until the very atoms themselves are crushed. The enormous gravitational pressure overcomes the Weak Nuclear Force, so that electrons fall out of their orbit and touch the protons … Continue reading →
