This 5-minute exposure shows Stuart Parker’s latest supernova discovery in spiral galaxy PGC 17517. Stuart Parker photo New Zealand amateur astronomer Stuart Parker just sent me an e-mail in which he announced his fourth supernova discovery. Parker routinely surveys numerous galaxies as part of a regular search program. He discovered the magnitude 17.1 object October 18 in PGC 17517, a magnitude 13.6 galaxy in Pictor. PGC is an acronym that designates...

Perplexed by planets? Confused by cosmology? Baffled by black holes? Then send in your questions to Astronomy magazine at askastro@astronomy.com . If you have an astronomy question about observing, the planets, stars, cosmology, or astronomy history, send it in! Five are selected each month for publication in the Ask Astro section of Astronomy magazine. If your question is selected, we will forward it to an expert for his or her response. Then, the...

Three of the most luminous supernovae on record — 2006gy, 2005gj, and 2005ap — pose problems for theorists. For example, 2006gy’s peak luminosity reached 50 billion Suns. That’s 10 times brighter than the average type Ia supernova and 100 times brighter than a representative type II. And 2005ap was 2 times brighter still. What’s a theorist to do? In our January issue, I noted that astronomers suspected some of these events might be so-called “pair...