National Astronomical Observatory of Japan

Occultation of Aldebaran on April 1 (April, 2017)

April 1, 2017 30 minutes after sunset, the sky of Tokyo
Download: Medium resolution (2000 x 1265) High resolution (5500 x 3480)

Let’s Observe the Spectacle of Aldebaran Concealed by the Moon

In the evening of April 1, a thin 4 day old Moon hides the 1st magnitude star Aldebaran in the constellation Taurus, causing an “Occultation of Aldebaran.” This time, you can observe the occultation of Aldebaran from anywhere in Japan. The disappearance and the reappearance will occur at medium height in the sky where you can see them easily. But, the sky is still light when Aldebaran disappears, so you might not be able to find Aldebaran with the naked eye. If you find Aldebaran, using the Moon as a guide, with a telescope or binoculars, you can observe the moment of “disappearance” when Aldebaran suddenly vanishes behind the dark edge of the Moon.

As seen from Tokyo, this “disappearance” occurs at 18:45 and “reappearance” (Aldebaran emerges from behind the bright edge of the Moon) occurs at 19:53. After the reappearance, the sky will be dark enough that you can see orange Aldebaran shining right next to the Moon.

The times for the disappearance and reappearance differ from place to place. Here are the predicted times, the altitudes, and visual guides for the occultation of Aldebaran at major locations in Japan.

LocationDisappearance (Elevation of Aldebaran)Reappearance (Elevation of Aldebaran)
NahaApril 1, 18:42.8 (56.9deg) April 1, 19:35.0 (45.3deg)
FukuokaApril 1, 18:33.2 (54.7deg) April 1, 19:44.6 (40.2deg)
KyotoApril 1, 18:40.1 (48.7deg) April 1, 19:50.1 (34.6deg)
TokyoApril 1, 18:45.0 (44.4deg) April 1, 19:53.2 (30.6deg)
SendaiApril 1, 18:44.4 (43.1deg) April 1, 19:51.5 (30.0deg)
SapporoApril 1, 18:42.9 (41.7deg) April 1, 19:44.9 (30.6deg)
Occultation of Aldebaran in Japan
Download: Medium resolution (2000 x 1265) High resolution (5500 x 3480)

This time the entire phenomenon, from disappearance to reappearance, ends before late at night, so even small children can stay up and observe the entire phenomenon. How about watching it with your family?

Reference: Ephemeris Computation Office

You can find the appearance of the Moon and planets as seen from a typical city under “Sky Viewer.”