Lunar Occultation of Mars

Verna and I witnessed the occultation of Planet Mars by Earth’s Moon this evening. At about 7:32 PM Arizona Time, Mars could be seen to disappear behind the Moon and would emerge again about an hour later on the opposite side of the Moon. In the image above (courtesy Griffith Observatory) you can see the tiny Martian dot just below and to the left of the Lunar limb. This is just about the same as we saw it around 7:30PM tonight. We came back outside at 8:30PM and witnessed the re-appearance of the Martian dot on the upper right Lunar limb – very impressive (and nerdy). We both enjoyed it and commented that it was a fun thing to do. We also had witnessed a visible flyover of the International Space Station about fifteen minutes prior to the beginning of the occultation.

From In The Sky — About this occultation:

The Moon will pass in front of Mars, creating a lunar occultation visible from parts of the Americas, Europe and Northern Africa.

Lunar occultations are only ever visible from a small fraction of the Earth’s surface. Since the Moon is much closer to the Earth than other celestial objects, its exact position in the sky differs depending on your exact location on Earth due to its large parallax. The position of the Moon as seen from two points on opposite sides of the Earth varies by up to two degrees, or four times the diameter of the full moon.

This means that if the Moon is aligned to pass in front of a particular object for an observer on one side of the Earth, it will appear up to two degrees away from that object on the other side of the Earth.

At the time of the occultation, the Moon will be 15 days past new moon and will be 100% illuminated.