Though February is the shortest month of the year, it is certainly far from least interesting. This month, the giant planet Jupiter is in opposition; Venus and Mars are in conjunction; the dwarf planets, Ceres and Pluto, which are due to receive their first visit by space probes, are both present at dawn.
Ceres and Pluto in the morning sky
On February 15 and 16, if you look to the southwest horizon at dawn you’ll see a thin lunar crescent shining among the stars of Sagittarius, right next to the dwarf planets Ceres and Pluto. While the Moon is visible to the eye, a telescope is required to see these dwarfs, which present an observing challenge – especially in the case of distant Pluto.
Giuseppe Piazzi, an astronomer at the Observatory of Palermo, Sicily, discovered Ceres on January 1, 1801. At first, Piazzi thought he had found a comet, but subsequent observations revealed that the object behaved more like the legendary “missing planet,” which was believed to exist between the orbits of Mars and Jupiter. The new “planet,” named Ceres, was eventually downgraded to the status of asteroid some fifty years later, after a number of similar objects were discovered in the same region of the Solar System – objects such as Pallas, Juno and Vesta. However, in 2006, the asteroid Ceres was again reclassified as a dwarf planet because of its large size and spherical shape.
In 2010, a space probe named Dawn visited Vesta and was originally scheduled to begin orbiting Ceres on March 6, 2015. But because of delays, Dawn will finally enter orbit 13 500 km above Ceres, on April 22. At that point, we should receive unprecedented images of the first dwarf planet ever discovered!
And who isn’t familiar with Pluto, long held to be the ninth planet in our solar system? It was also demoted to Dwarf planet in 2006. American astronomer Clyde Tombaugh discovered Pluto in 1930, at the Lowell Observatory, Arizona, and its name was proposed by an 11 year-old British girl named Venetia Burney. Located in the Kuiper belt beyond the orbit of Neptune, Pluto is an intriguing world orbited by no less than 5 moons. Charon, which was discovered in 1978, remained Pluto’s only satellite until 2005 when Hydra and Nix were observed: These two moons were followed by the discovery of Kerberos in 2011, and Styx in 2012. The names were chosen for characters in Greek mythology who were associated with the god of the underworld, and ratified by the International Astronomical Union.
The New Horizons probe, launched in 2006, will become the second spacecraft to study a dwarf planet when it passes Pluto and its moons in July, and it will be the first to send back pictures from that far away in the Solar System. Because Pluto is nearly 5 billion kilometers from Earth, those pictures will take four-and-a-half hours to reach us. So far, all we know about Pluto is that it’s covered in frozen methane, nitrogen, carbon monoxide, ethane and water. New Horizons promises to reveal new details about the origin of our solar system, and how the icy worlds of the Kuiper belt have evolved over time.
A giant in opposition
On February 6, Jupiter is in opposition… in other words, it’s directly opposite the Sun as seen from Earth. Because Jupiter will then be closest to us, this is also the best period to observe and photograph the giant planet and its moons. A good pair of binoculars should reveal the four Galilean satellites, which appear like tiny points of light next to the planet; if not, then any small telescope will do the trick.
A meeting of two planets
Conjunctions occur when two or more planets appear very close in the sky. On the evening of February 22, Venus and Mars will be just half-a-degree from each other, set against the stars of Pisces. Look toward the western horizon shortly after sunset: Brilliant Venus will guide you to the much fainter Red Planet shining below.
The Moon across the sky
On February 3, the full moon will be near Jupiter, shining among the stars of Cancer. Try not to miss them rising in the eastern twilight: It should be a spectacular sight. The following evening, the gibbous moon will appear next to the star Regulus, in Leo; then, early on the mornings of February 9 and 10, it will be near Spica in Virgo. The last lunar quarter phase will occur on February 11, and the Moon will be new again on the 18th: It will take a couple of days before the lunar crescent becomes visible again, after sunset. At twilight, on the evening of February 20, look for a resplendent celestial trio, consisting of Mars (on top), Venus (at the bottom) and a thin crescent moon (to the right). On the evenings of February 24 and 25, in the southwest, the first lunar quarter will form a large triangle, together with the Pleiades cluster and the red giant star Aldebaran, all in the constellation of Taurus.
Clear skies to all!
Planets visible to the naked eye