With the exception of Mars, all of the other easily-visible plan-ets are in the evening sky. We start with Venus and Mercury which are playing tag in the west-southwest just as the Sun sets. Look quickly as the pair are quite low. For most of the month Venus sets at 7pm CDT with Mercury to the left, about 45 minutes after sunset. On October 1, the pair is far to the lower right of the crescent Moon. As we progress through October, the pair keep their same orientation but move farther to the southwest. On the 19th, Mercury is at its greatest separation from the Sun but unfortunately this is along the horizon and not perpendicular to it. After the 24th, they start getting closer to-gether. On the 29th, a very thin crescent Moon makes a triangle with Venus and Mercury below. If you haven’t seen Venus yet, use the Moon as your guide. By Halloween, Venus is directly above Mercury in relationship to the horizon by about 2.5 de-grees. Again, both planets are low, but Venus is at magnitude -3.9, much brighter than Jupiter (-1.9). Remember we have the transit of Mercury across the Sun next month – do we want to do any organized observing?
Jupiter and Saturn are higher in the sky than Venus, but have you noticed them both being farther to the southwest? Jupi-ter’s set time goes from 3.5 to 2.4 hours after the Sun this month. Jupiter is slowly heading eastward in front of the stars of Ophiuchus. Check out the crescent Moon near Jupiter on October 3rd. The pair will be close! Though it won’t be as close, the gathering repeats itself on Halloween night. Hey, why not get out your telescope and share Jupiter and the Moon with trick-or-treaters?
Saturn reaches “Quadrature” on October 7th which may mean very little to the casual observer. Basically a line drawn from the Sun to the Earth and then another from the Earth to Saturn make a right angle. For those with telescopes, the Sun’s light is hitting Saturn in such a way that the planet casts a visible shad-ow on the ring system. Use high magnification and look for this effect. I would bet that Saturn will draw the attention of many telescopes at our October 5th open house. The rings are tilted just over 25 degrees to our line-of-sight.
Late in the month (the 27th), the planet Uranus reaches opposi-tion in the constellation of Aries. At magnitude 5.7, you might be able to pick it up with binoculars if you know where to look. Aries is beneath Andromeda and east of the Great Square of Pegasus. You can see a finder charts for both Uranus and Nep-tune at: https://s22380.pcdn.co/wp-content/uploads/WEB_UrNep_2019-2020_updated.pdf. Also check out this month’s Night Sky Network article. Don’t look around the 14th as the bright Moon is in the way.
Mars returned to the morning sky last month though it’s higher now. Its rise time goes from 8am at the beginning of October to 5:45am near the end of the month, before the morning twilight. Mars is traversing Virgo fairly quickly. Look for a very thin Moon above Mars on the morning of the 26th. At magnitude +1.8, it’s not as bright as Jupiter or Saturn but that will change as we head into next year. On the 7th, the northern hemisphere of Mars experiences the summer solstice!
We have a somewhat major meteor shower this month as the Orionids peak on the evening of the 21st and the morning of the 22nd. The Orionids result from the Earth passing through the dust trail of Halley’s Comet. Of course, the comet itself doesn’t come back until 2061 but the dust from the comet has spread out along its orbit. As the Earth hits the dust at high velocity the particles ionize the Earth’s air, giving us the glowing trail of a meteor. The radiant point is near the club of Orion and it rises before 11pm on the 21st but you should see more meteors after midnight. Estimates are in the 20 per hour range. The waning crescent Moon won’t brighten the sky too much giving us good skies for meteor watching. Find the darkest spot you can. If you see any bright fireballs in the sky earlier in the month, they could be from the Southern Taurid shower, not near as well known.
Did you hear about this interstellar comet? Comet Borisov will be closest to our Earth in December but that’s still at twice the Earth/Sun distance. The comet was discovered at the end of August using a 65-cm telescope. Further observations revealed its odd hyperbolic orbit. Currently at magnitude +17 it’s not expected to brighten much more than +15, which is pretty faint. But you never know!