SKY GUIDE:  This chart represents the sky as it appears over Maine during October.  The stars are shown as they appear at 10:30 p.m. early in the month,  at 9:30 p.m. at midmonth and at 8:30 p.m. at month’s end.  Mars, Saturn and Jupiter are shown in their midmonth positions.  To use the map, hold it vertically and turn it so that the direction you are facing is at the bottom.  Sky chart prepared by George Ayers

October is when famous flaming foliage peaks for us in New England each year. Just as autumn is now transforming our landscape and cooling our air, the sky above is also changing as fall and winter constellations are rotating into view to set the stage for a new season.

This month brings with it more than the usual share of interesting highlights. The bonus this particular October will be Mars at its most dazzling in 17 years. Then you have Jupiter and Saturn getting a little closer each night, Uranus at opposition in Aries, two full moons including a blue moon on Halloween, an asteroid named Flora at opposition, the usual close conjunctions of the moon with some of the planets, a very close conjunction of Venus and Regulus, and favorable conditions for not one, but two meteor showers – the Draconids on the Oct. 8 and the Orionids on Oct. 21.

Mars will be the magnificent star on our celestial stage for all of this month. It doubled in brightness last month as the earth was rapidly catching up with the red planet in our respective orbits, and now that we have caught it, it will even outshine Jupiter. Mars will be closest to Earth on the Oct. 6 and it will reach opposition on Oct. 13, when it will rise at sunset and not set until sunrise. This only happens once every 26 months, based on how we both orbit the sun, but some of these oppositions can be much better than others. This will be one of the best. Although not as close as the last one in July of 2018, which was a perihelic opposition, meaning that its perihelion or closest approach to the sun coincided with its closest approach to Earth, this one will be fully 30 degrees higher above our horizon, allowing for much better views of our neighboring and still mysterious planet.

Mars will be 39 million miles away at this opposition. To put that into a good comparison scale to picture it and not just think of a number, that is the equivalent of about 5,000 earth diameters. The earth is 8,000 miles in diameter and 25,000 miles in circumference. The sun is nearly 12,000 earth diameters away on the average. The moon is just 30 earth-diameters away. Mars will even outshine Jupiter for a while this month and its apparent diameter will reach 22 arc seconds of the sky, or nearly half a minute. 30 arc minutes is half a degree, which is the size of the full moon and the sun.

The last good opposition before the July 2018 perihelic opposition was on Aug. 27, 2003. That was the closest approach of Mars in nearly 60,000 years, about the time modern humans started migrating east out of Africa. Mars was only 35 million miles away then, but a long-standing rumor started circulating on the web then that Mars would become as large as the full moon in our sky. Mars, which is half the size of the earth, would have had to get within just 83 earth diameters instead of the actual 5,000 earth diameters. That is about 60 times closer than it actually got. It might have been an honest mistake if they just mixed up arc seconds and arc minutes, which is a factor of 60. In any case, it is a good exercise in understanding relative size and scale of some of our nearby neighbors in our solar system.

You will still need a telescope to enjoy all the features now visible on Mars during this great opposition. Look for dark markings and both the north and south polar icecaps. The south polar cap is mostly frozen carbon dioxide, or dry ice. It is summer at the South Pole now, so it will be smaller than usual. I already saw some of these markings through several telescopes at our club’s last event a few weeks ago. Not many of us showed up, but it was good to see everyone again “live” outside and with masks on. We also enjoyed great views of Jupiter and Saturn and many popular favorite celestial objects like the Andromeda Galaxy and the great globular cluster in Hercules along with several nice planetary nebulae, which is a look into the distant future of what our own sun will turn into when it finally runs out of fuel in about 5 billion years.

You may even see the faint outline of Olympus Mons, the biggest volcano in the entire solar system, fully three times the height of Mt. Everest at 90,000 feet or 17 miles high. The whole mound covers the size of France. Then you may also see one or both of the small Martian moons, Phobos and Deimos, which means Fear and Terror. Phobos is slightly larger and brighter, but it is very close to the planet at only 3,700 miles, so it is hard to see over the glare of Mars. Phobos is about 14 miles in diameter and Deimos is only 8 miles across. Deimos is much farther away from Mars, so it is easier to see. Based on what we know about gravity and orbital mechanics, Phobos is getting a little closer to Mars each year and in about 50 million years it will either crash into Mars or be torn up by its gravity into a ring of rubble.

While you are enjoying this close opposition of Mars, be aware that three different countries have recently successfully launched a whole armada of scientific exploratory missions. NASA has the Perseverance Rover with a drone that will fly in the very thin Martian atmosphere, the United Arab Emirates have HOPE, which will just orbit Mars and not land, then China has Tianwen 1, which means “questions to heaven.” That is the heaviest payload ever launched to Mars and contains an orbiter, a lander and a rover. So humans will have invaded Mars remotely by late winter of 2021, instead of the Martians invading us. The result will be a lot of great scientific data and a much deeper understanding of this planet which will better prepare us for sending humans there safely in just 15 more years.

So dust off your telescopes or borrow one from a library or a friend or an astronomy club and enjoy this rare showing of Mars. The next time it will be this close and high in our sky will be in 2035, just about the time NASA has scheduled the first humans to land on Mars.

Both Jupiter and Saturn are now back to their direct or eastward motion. They are both easily visible high in the south as soon as it gets dark enough, before any other stars become visible. Watch how the closer and faster-moving Jupiter is catching up with Saturn. That will culminate on the winter solstice, when they will be just a quarter of a degree apart, their closest conjunction in about 400 years, since the invention of the telescope and modern science began.

The planet Uranus will reach opposition in Aries on Halloween. It will reach a magnitude of 5.7, so it should even be visible without binoculars. It will cover just 3.8 arc seconds of the sky, or 6 times smaller than Mars. It is tilted 97.8 degrees on it axis, so it appears to be rolling along the ecliptic. It exhibits a lovely pale blue color in a telescope.

Venus will pass within half a degree of Regulus in Leo on Oct. 2. That is the width of the full moon. I could see the star Regulus in the daytime very close to the sun along with several planets that instantly popped into view when it was completely covered by the moon during the total solar eclipse on Aug. 21, 2017. I drove all the way to eastern Idaho to see that and it was well worth every second of my trip. Everyone should see a total solar eclipse at least once in their lifetimes. You will learn more about the sun, moon, and planets and the inner workings of our solar system during those few brief moments of being immersed in the moon’s shadow than you ever could by just studying math and physics or watching movies of eclipses.

The Orionid meteor shower will peak on Wednesday, Oct. 21 at around 2 a.m. The conditions are favorable this year with no moonlight to see 15 meteors per hour from a dark sky site. These are tiny, sand grain-sized pieces of Halley’s Comet disintegrating high in our atmosphere at 148,000 mph, or twice the speed that the earth is always orbiting the sun.

The radiant of this shower is in the club of Orion. So you could picture Orion the mighty hunter hurling these meteors at the earth or batting them towards us with his club. Halley’s Comet also causes the Eta Aquarids on May 5 each year. The entire comet will not return again until 2062.

Oct.1: The full moon is at 5:06 p.m. This is also called the famous Harvest Moon because it is closer to the equinox than last month’s full moon was. The Yerkes 40 inch refracting telescope was dedicated on this day in 1897. Designed by George Ellery Hale, it was the largest telescope in the world at the time and is still the largest refractor in the world even now.

Oct. 2: Mars will rise with the moon tonight right after sunset. Venus will pass within half a degree of Regulus this morning.

Oct. 4: On this day in 1957, Sputnik 1 was launched by the Russians.

Oct. 8: The Draconid meteor shower peaks tonight.

Oct. 9: The last quarter moon is at 8:41 p.m.

Oct. 13: Mars is at opposition.

Oct. 14: Venus rises close to the waning crescent moon this morning around 4 a.m.

Oct. 16: The new moon is at 3:32 p.m.

Oct. 21: The Orionid meteor shower peaks at 2 a.m.

Oct. 23: The first quarter moon is at 9:24 a.m.

Oct 31: On this date in 2005, the Hubble Space Telescope discovered two more moons of Pluto, Nix and Hydra. The second full moon of this month, also called a Blue Moon, happens at 10:50 a.m.