Chris Miskiewicz announced that he would be opening one of the Howard Astronomical League dark sites last Monday morning to observe the close conjunction of Venus and Jupiter. I set an alarm for 3:15am, and immediately went outside to check the weather. Upon determining that it was mostly cloudy, I thought it not worth the effort, so I tried to go back to sleep. Fifteen minutes later, I felt that I could not go back to sleep and I knew that Chris would be at the site no matter what, so I jumped in the Jeep and drove out there. The conjoined planets had not yet risen above the eastern horizon when I arrived, but the sky was mostly clear in the area where they would be rising in about 20 minutes. While waiting for them to rise, I took in Orion and the waning crescent moon, which were both already well above the horizon in the same area. They were a beautiful pair both with the unaided eye and in the telescope, so this was a very rewarding trip! Chris’ image below is very close to what I saw without the telescope. I packed up my equipment and headed toward my day job at about 5:35am.
The actual conjunctions, the two planets’ closest approach to one another, occurs before they rise right before dawn. At conjunction, they are separated by .2 degrees. Their separation will have increased to .5 degrees, the width of the full Moon, and will still present a pretty pair when they rise in the east shortly before sunrise.
To the casual observer, the planets are indistinguishable from bright stars. For the purposes of our unaided eye observation, the stars remain fixed in place relative to one another. Even without magnification, planets can be observed to move among the stars as they move along their orbital paths around the Sun. Movement of the planets closer to the Sun, which orbit the Sun faster than the planets that are farther from the Sun, can be detected from one night to the next. The motions of the planets more distant from the Sun can be detected over the course of weeks or months. I have actually seen Venus’ movement over the span of a few minutes through a telescope during the 2012 transit of Venus across the face of the Sun. Even when greatly magnified, stars will never appear as more than a single point of light when observed from Earth. Planets on the other hand, will appear larger with magnification, and a disk can be observed. Features on some of these disks can be observed with sufficient magnification.