The Moon and Planets
When the waning gibbous moon rises tonight (Sunday) in mid-evening, it will sit to the upper right of the stars that form the triangular face of Taurus (the Bull). Through the night and into Monday morning, the moon will approach and then pass among them. Observers in central and northeastern Asia will get to see the moon pass in front of (or occult) the bright star Aldebaran, which represents one of the bull’s eyes, in the early hours of Tuesday morning.
The moon reaches its Last Quarter phase on Thursday morning. At that time, it will be half illuminated on the left (its west) side and rising in the middle of the night to linger into the morning daylight sky. This leaves our evening sky nice and dark for meteor hunting.
In the eastern pre-dawn sky next Sunday, October 15, much of North America will see the lit leading edge of the old crescent moon pass over the bright star Regulus in Leo (the Lion). The star will reappear from behind the dark limb about an hour later. Times and durations vary by region. Observers in the Great Lakes region will see the event start at 5:45 am EDT and end in twilight at 6:33 am. Out west, observers will witness a shorter occultation. Start looking a few minutes beforehand. A backyard telescope will work well for this event, but don’t enlarge the moon too much — you’ll want its entire disk is in view for the emergence.
If you spot something bright and unblinking sitting very low in the western sky after sunset this week, it’s likely Jupiter. The giant planet sets about 40 minutes after the sun, at about 7:10 pm local time. The view of Jupiter will be heavily distorted because we have to look through such a deep blanket of air when it is sitting so low. Towards the end of October, Jupiter passes the sun. Then it will move into the pre-dawn eastern sky, making a fantastic pairing with Venus on November 13.
Saturn is the brightest object partway up the southern sky as the evening darkens. It sets in the west about 10 pm local time. We’ve only got another month before it begins to sink into the twilight, so enjoy it now. Tiny blue Neptune is observable from mid-evening until 4 am. It is located in the southeastern evening sky about two finger widths to the lower left of the medium-bright star Hydor in Aquarius (the Water-Bearer). But it is too faint to be seen without a telescope.
Blue-green Uranus is situated about halfway along the eastern (left-hand) string of stars that form Pisces (the Fishes). It’s low in the east at dusk and is observable for the rest of the night in binoculars under a dark sky. Next week, the planet will be closest and brightest for this year. To help guide you, there’s a medium-bright star called Omicron Piscium about a finger’s width below Uranus.
As this week begins, extremely bright Venus is still nicely paired with much fainter reddish Mars in the eastern pre-dawn sky. Venus is dropping daily as it swings sunwards, so it is moving steadily away from Mars every morning. Look for the two planets from about 5:45 am to 6:45 am local time.
Orionid Meteor Shower
One of this year’s best meteor showers, the annual Orionids, is underway until November 14 and is observable world-wide. It peaks after midnight on October 22, when the sky overhead is moving directly into the densest region of the particle field, which is derived from material left by repeated passages of Comet Halley. The meteors can appear anywhere in the sky, but will be moving in a direction away from a location (the radiant) above the bright red star Betelgeuse in the constellation of Orion. Orionids are known for being not too prolific (the hourly rate at the peak is only 25), but they are usually bright and fast-moving.
Luckily this year, the Moon will be new around the peak evenings, leaving us a nice dark sky. To see the most meteors, find a wide-open dark location, preferably away from light polluted skies, and just look up. Binoculars and telescopes are not useful. If the peak night is cloudy, a day or two on either side is almost as good. You can start watching now! Happy hunting!
Iridium flares are glints of sunlight off of the flat reflecting sides of one of the satellites that comprise the Iridium pager and sat-phone network. The flares occur before dawn and after dusk, when the satellite passing overhead is still illuminated by the Sun, which is below the horizon for observers on the ground. The duration and brightness depend on the angles between the observer, the satellite, and the Sun. For even more info about Iridium Flares and the space station, see an article that I wrote here.
The Iridium company has started replacing these satellites, so enjoy them while you can. Using an accurate clock, go outside a few minutes ahead and look in the direction indicated. You should first see the dim Iridium satellite moving quickly across the sky, and then it will rapidly brighten for 3 to 8 seconds, and fade out. Truly spectacular! The more negative the Magnitude number, the brighter. The larger the Alt. number, the higher up it is! (The horizon is 0°, and 90° is straight up, so 55° is a bit higher than halfway between the horizon and zenith.)
Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.
Stargazing News for this week (from October 8th, 2017) by Chris Vaughan.