I've always loved solving mysteries. I find myself often using Starry Night® as a tool to solve astronomical mysteries. In recent months I've been visiting the Yahoo!Answers web site:
This is a place where people can ask questions on just about any topic and receive answers from other users. Naturally, I spend most of my time in the "Astronomy & Space" category, located under "Science & Mathematics." Often I find Starry Night® an enormous help in answering people's questions about the sky.
Many of the questions are of the form "Last night I saw a bright star in the sky—what was it?" In itself this isn't enough information to provide an answer, so I often need to ask for more information:
- Where are you located?
- What time of night was this?
- What direction was the star in?
- How high was it?
With this information in hand, I can set Starry Night® to the questioner's location, date, and time. Usually, by looking in the right direction and altitude I can figure out what the star was, allowing for the fact that many towns use local conventions for directions which may not agree with the compass directions. For example, in Montréal, where I grew up, streets which the local people describe as running east and west actually run almost north and south. This is because "east" and "west" are defined locally by the direction the St. Lawrence River flows, which is actually north to south at Montréal's location!
There were a couple of interesting questions recently. One was from a person in Ireland asking about two bright objects in the west just after sunset. Using Starry Night® I was easily able to identify these as Jupiter (above and to the left) and Venus (below and to the right). I suggested that he keep an eye on them for the rest of the month, and I suggest that you do too. Over the next couple of weeks they will draw together and pass each other and, on the night they pass, December 1, they will be joined by the crescent Moon, forming a tight 2 degree group, which should be a very pretty sight in binoculars or a small telescope (Venus and Jupiter have been slightly enlarged in this image):
The other question was more of a puzzler. The questioner asked why the Moon appeared so odd lately. He said that the line cutting the Moon in half (what astronomers call the terminator) was horizontal rather than vertical. It turned out that he lives in Florida, and this is what Starry Night® showed:
Lo and behold: the terminator is horizontal! How can this be? By zooming out and making the horizon translucent, we can see what is actually going on:
As seen from Florida in November, the Sun is actually directly below the Moon as it rises, so the terminator runs from left to right, rather than from top to bottom. Mystery solved!
Geoff has been a life-long telescope addict, and is active in many areas of visual observation; he is a moderator of the Yahoo "Talking Telescopes" group.