Now that autumn leaves are falling, the skyline is less obstructed and the time is right for early birds to catch the planets dancing on the horizon. Flamboyant Venus and Jupiter; Mars the Red Planet; and even elusive Mercury are all dazzling in the dawn sky. Observing a planetary conjunction has never been easier. The hard part is getting out of bed.
Venus, Mars and Jupiter in Conjunction
The dance begins on October 9. A thin lunar crescent rises at 4:00 A.M. (though it’s easier to see at 5:00) and will guide you toward the planetary trio. Blazing Venus soars above the Moon on the eastern horizon and is easily the brightest star-like object in the sky. To the Moon’s left, but slightly closer than Venus, there’s a faint red star… in fact, it’s actually the planet Mars. Now don’t get distracted by Regulus, the brightest star in the constellation Leo. Regulus is slightly brighter than Mars and sits to the upper left of Venus. Lastly, Jupiter the lowest of the three planets, rises to form an isosceles triangle with Mars and the Moon.
On October 9, if the clouds or your alarm clock refuse to cooperate, do not despair! When the planets get together it’s usually for more than just a quick breakfast.
Two days later, before sunrise on Sunday October 11, it’s Mercury’s turn to greet the Moon. This is a rare opportunity to spot Mercury in the sky, since it’s never far from the Sun and always in the glow of twilight. A few days later, on October 16, the tiny planet reaches its maximum elongation—its greatest distance from the Sun as seen from Earth—which is the best time to observe it.
Continuing in the east, on the mornings surrounding Saturday October 17, Jupiter joins Mars. Viewed from Earth, the gas giant appears less than a lunar diameter below the Red Planet despite the 600 million odd kilometers that separate them in reality.
Over the following days, the two planets gradually approach Venus, whose upward climb slows as it approaches its greatest elongation on October 26. On the same date, Venus and Jupiter will be closest to one another in the sky. Try not to miss this spectacular encounter between the two brightest planets!
This planetary dance will continue into the month of November, when Mars joins Venus and the Moon.
The evening is more relaxed
This October, the evening sky will be less active. Following the new moon on October 12, the waxing phases will be visible at nightfall, until the full moon on the 27th.
As for the planets, we lose sight of Saturn, which is now setting too early to see... and that leaves Uranus and Neptune. Uranus is closest to Earth on October 12, but still a respectable 2.84 billion kilometers away! Though a dark sky, free of light pollution, might afford a glimpse of the planet among the stars of Pisces, most observers will need to use binoculars to appreciate the tiny turquoise dot of light we call Uranus.
A galaxy not so close to home…
As far away as Uranus and Neptune may seem, the real “star” of October skies is much farther, yet visible from our backyards. The Andromeda galaxy, known as M31 in the Messier catalogue of celestial objects, is generally considered the most distant object visible to the naked eye.
Galaxies are groupings of billions of stars, and the most impressive ones take the form of spheres or spirals. Our galaxy, the Milky Way, contains up to 400 billion stars: Our star the Sun, and its planetary system, are microscopic compared to the scale of our galactic spiral. Andromeda, another spiral, is twice the diameter of the Milky Way, and is the closest large galaxy to us.
In our sky, the Andromeda galaxy appears in the constellation of the same name, but it’s easier to use Cassiopeia to spot it. Cassiopeia forms a “W” that’s easy to locate near the zenith on autumn nights. Follow the point of the right-hand “V” in the “W” about three lengths to find M31. If you are under a sufficiently dark sky, you’ll spot a small cloud that immediately captures your attention… it’s even visible from the city using binoculars.
Don’t expect to see a stunning object, like you would in an astronomy magazine. None-the-less, this small hazy patch is indeed the Andromeda galaxy. It’s the light of a trillion stars that travelled over 2.5 million years before reaching your eyes. In comparison, the light coming from the stars of Cassiopeia takes a few hundred years; the light from Uranus takes 2 hours, 36 minutes; and that of the Moon, just 1.3 seconds! Happy contemplating, and…