By Dennis Mammana- It was on the first day of the 19th century that the Italian priest, mathematician and astronomer Giuseppe Piazzi found a strange object in the sky that no one had ever seen before — an “intruder” among the familiar stars of the constellation Taurus, the bull.
After waiting several nights, he returned to the telescope and found that the object had moved.
Piazzi named the new body “Ceres” after the Roman goddess of agriculture and protector of Sicily, but what he had found was a total mystery.
At first, Piazzi thought he had discovered a comet; then astronomers suspected it might actually be a planet. It wasn’t until the 1850s, however, that they found similar bodies between the orbits of Mars and Jupiter and classified them all as asteroids.
Recently, Ceres, with a diameter of barely 588 miles, was reclassified as a dwarf planet — along with our friend Pluto — and even received a visitor in the form of a robotic spacecraft named Dawn, which orbited the small body and radioed back remarkable photos and other data to scientists on Earth.
This week, Ceres reaches its opposition point in its orbit around the sun, rising in the east as the sun sets in the west. It now appears about twice as faint as the dimmest stars we can see with the unaided eye, but it’s well within the range of binoculars.
To search for Ceres, head outdoors this week around 9 or 10 p.m. and find the constellation of Scorpius, the scorpion, low in the southeastern sky.
The Scorpion’s image is one of the oldest of the Egyptian hieroglyphics, and it appears in inscriptions predating the third millennium B.C. In Greek and Roman mythology, Scorpius represented the creature whose sting caused the death of the great hunter Orion, a prominent celestial symbol of winter. It’s quite easy to trace its claws and long-curving tail, as well as the reddish-orange star Antares marking the heart of the celestial arachnid.
Once you find Scorpius (use the accompanying illustration to help you do so), identify the three fainter stars that form a line just to its east. These are named Phi Ophiuchi, Chi Ophiuchi and Psi Ophiuchi.
If you aim your binoculars toward the middle of these stars this week and place Chi at the center, Ceres will appear nearby — but considerably fainter.
Because Ceres moves around the sun, its orbital motion is detectable as it drifts among the stars from night to night, so check it out the next night and the next. You can even make a sketch of the binocular starfield for later comparison. This works best if you can mount your binoculars on a tripod.
If you want a more detailed and accurate map of that part of the sky and wish to plot Ceres’ position on any night you choose, visit in-the-sky.org/findercharts.php. Here, you’ll be able to enter Ceres’ name, your location, date and time and print out any kind of map you like.
If the star you thought was Ceres has indeed moved, you’ve found it. And my guess is that you’ll be just as excited as Piazzi must have been 218 years ago! Visit Dennis Mammana at dennismammana.com.