Conjunction of Venus and Jupiter

Venus and Jupiter will have a conjunction at the beginning of the month of December. What is a conjunction? There are many uses of the term in astronomy, and here we use it to describe when two planets are very near to each other because they are on the same line of "longitude." I put the word longitude in quotes because in astronomy, we use a coordinate system similar to latitude and longitude, but the proper names are declination and right ascension. Therefore, when two planets have the same right ascension, we call that a conjunction.

The sketch (made by my daughter) depicts the sky as it will appear shortly after sunset on November 30th just as Jupiter and Venus are moving toward their closest approach. The scene will be made all the more beautiful by a young crescent moon just below the two planets. The next night, December 1st, the Moon will have moved just to the left and above the two planets. Both nights will be perfect for telescopic viewing, as the young Moon with its cratered surface (usually accompanied by earthshine) is always a beautiful sight, and you can see Venus at gibbous phase and Jupiter with its four bright moons. As mentioned in a previous post, these three objects with their special traits are three of Galileo's most famous discoveries with his telescope in the early seventeenth century.