Aurora Alert Tonight Oct. 1-2 / See The Moon Cover Aldebaran Friday Morning

Binocular view of the Hyades Star Cluster with the waning gibbous moon on the verge of occulting the star Gamma Tauri just after midnight CDT for northern Wisconsin-N. Minn. Source: Stellarium
Binocular view of the Hyades Star Cluster with the waning gibbous moon on the verge of occulting the star Gamma Tauri just after midnight CDT for northern Wisconsin-N. Minn. Source: Stellarium

* Update: Just looking this morning at 8 a.m. CDT and Aldebaran is incredibly easy to see in my 6-inch scope 40 minutes before its occultation with the sun shining away in the east. Nice contrast between the orange star and blue sky! See below for full story.

Minor storm conditions are expected later tonight as the solar winds blow Earth’s way. Skywatchers in the northern U.S. may see a touch of good-luck green in the northern sky. If you don’t get aurora, you’ll at least get to see the moon pass through the Hyades star cluster late tonight / early tomorrow morning depending on your time zone. For points north of about 45° north (Minneapolis), the star Gamma Tauri, located at the junction of the “V” that forms the Hyades star cluster, will disappear in an instant when the bright edge of the waning moon covers it about 12:10 a.m. CDT Friday (Add 1 hour for EDT, subtract an hour for MDT and 2 hours for PDT).

Aldebaran Duluth 8_42am
Taurus’s brightest star Aldebaran will be occulted by the moon after sunrise for the eastern two-thirds of the U.S..Here, Aldebaran is seen a minute or two before being covered up by the moon at 8:42 a.m. CDT Friday from Duluth, Minn. Source: Stellarium

Our satellite slowly crawls across the cluster throughout the night, occulting fainter cluster members for U.S. and southern Canadian skywatchers. But the real excitement happens after sunrise tomorrow morning, when it’s Aldebaran’s turn. Across the eastern two-thirds of the U.S. and Canada, the moon will cover up Aldebaran.

Have you ever seen a star in full daylight? If not, this may be your chance. You’ll need a small scope and a very clear, blue sky. Finding the moon will be easy. Just face the western sky and there it is. Point your telescope at it, focus and look above the bright limb for Aldebaran shortly before the time of occultation. Then track it until the star suddenly pops out of view. Roughly an hour later (more or less depending on your location), Aldebaran will reappear at the moon’s dark limb.

For the eastern half of the country, the moon will probably be too low to see the reappearance. Much further west, both disappearance and reappearance will be visible with the moon well up in the western sky. Observers in Nevada, California, California and Washington will have no difficulty seeing the occultation because it occurs in morning twilight. For Alaskan and far western Canadian observers it happens in a dark sky.

Four different views and times of the Aldebaran occultation as seen from four cities across the country. Source: Stellarium
Four different views showing Aldebaran a couple minutes before being occulted by the moon from four different cities across the country. Source: Stellarium

You check the International Occultation Timing Association’s (IOTA) page for times of disappearance and reappearance if you live where the event happens in deep twilight or night. Otherwise, here are times circumstances for several major cities that you can use to interpolate your location’s time:

* New York — Disappears at 10:01 a.m. EDT (Friday) with the Moon 20° high in the western sky
* Miami — Disappears at 10:32 a.m. EDT, Moon 16° high / Reappears at 10:56 a.m. EDT
* Chicago — Disappears at 8:53 a.m. CDT, Moon 31° high / Reappears at 9:55 a.m. CDT, Moon 20° high
* Denver — Disappears at 7:40 a.m. MDT, Moon 47° high / Reappears at 8:44 a.m. MDT, Moon 35° high
* Tucson — Disappears at 7:00 a.m. MST, Moon 50° high / Reappears at 7:24 a.m. MST, Moon 45° high
* Seattle — Disappears at 6:04 a.m. PDT, Moon 56° high / Reappears at 7:19 PDT, Moon 48° high

For more information and additional diagrams, please see my article in Sky and Telescope this week on the topic. Clear skies!