What’s Up for September? Mars on the move, prime viewing time for Jupiter, and a clever way to find your bearings on the equinox.
You’ll find Mars hanging out high in the south on September mornings before sunrise. Early in the month, it’s near orange-colored Aldebaran, the eye of Taurus the bull. And over the course of the month, Mars works its way eastward from Aldebaran toward reddish Betelgeuse, creating a sort of “red triangle” in the morning sky. Then the Red Planet will appear to hit the brakes and halt its eastward motion, to hang out in that triangle for the next month or so. (We’ll talk about what’s going on there in next month’s skywatching tips.)
On the morning of the 11th, before sunrise, you’ll find the Moon just a couple of finger-widths from Jupiter in the sky, making for a great viewing opportunity to observe them together through binoculars. Jupiter’s at opposition this month, making it visible all night under clear skies. And it’s around this time when the planet’s at its biggest and brightest for telescope viewing. But a pair of binoculars is enough to reveal the giant planet’s four large moons as little starlike points of light next to Jupiter.
And this month, NASA’s Jupiter-orbiting Juno spacecraft is slated to make a special, fast flyby of one of those icy moons, Europa, on the 29th. The spacecraft is planned to pass a little over 200 miles above the moon’s surface, returning images and science data.
Also, NASA is currently preparing its Europa Clipper spacecraft for launch in 2024. It’s planned to make dozens of close flybys of Europa to investigate whether the moon could have conditions suitable for life.
Turning to the evening sky, you’ll have Saturn together with Jupiter as your planetary companions all month long. On the night of the 9th, Jupiter and Saturn escort the Moon across the sky. You’ll find the trio rising in the southeast in the first couple of hours after dark, and gliding westward together over the course of the night. By the end of the month, you’ll find the pair of planets rising even earlier, appearing in the east soon after it gets dark, with bright Jupiter hanging low in the sky.
September 23rd brings the September equinox, which marks the start of fall in the Northern Hemisphere, and the start of spring in the Southern Hemisphere. The equinoxes occur twice per year when Earth’s tilt with respect to the Sun is the same for both hemispheres. Both north and south receive the same amount of sunlight, and day and night are, briefly, of nearly equal length.
And, get this: if you take note of exactly where the Sun appears to rise and set on the equinoxes, those points mark the locations of due east and due west, respectively.
And that’s something useful to know for skywatchers, whatever hemisphere you happen to live in. So take note of any buildings, tall trees, lampposts, and the like at those places on the horizon, and you can use them to find your bearings when looking skyward all year long.
Stay up to date with all of NASA’s missions to explore the solar system and beyond at nasa.gov. I’m Preston Dyches from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.