As the sky darkens, Venus and Jupiter appear low in the west. While the gap between the two planets is growing, they are both inching toward Regulus, with Venus two degrees below the star Monday and Tuesday.
Dusk reveals Saturn above the southern horizon with the three stars marking the head of Scorpius beneath it and Antares, the heart of the scorpion, a dozen degrees below.
Mercury makes an early morning appearance low in the east-northeast a half-hour before sunrise. Don’t confuse Mercury with the much-dimmer star Aldebaran, the red eye of Taurus the bull, high above to the planet’s right. Aldebaran is visited by the thin waning crescent moon before dawn Sunday.
While you’d need a massive telescope to see it from your back yard, eyes will be on Pluto this week, as NASA’s New Horizons spacecraft, launched in 2006, comes its closest to the distant planetoid Tuesday after a three-billion-mile journey. Back then, Pluto was still the ninth planet. As I wrote at the time:
Thursday, January 19, NASA launched the space-probe New Horizons on a nine-year mission to our solar system’s outermost planet, Pluto. Discovered by Clyde Tombaugh in 1930, Pluto is also the last planet not viewed by a passing earthen spacecraft.
Two weather delays were not the only pressures weighing on the launch. The project sparked debate over the craft’s plutonium-powered engines and a possible lift-off explosion. But as New Horizons safely cleared earth orbit, it carried another payload, one closing the cosmic loop: a tiny canister bearing cremated remains of Clyde Tombaugh.
Over the next five months, New Horizons will study Pluto and its moons, of which there are at least four detected by the Hubble Space Telescope. According to NASA, astronomers hope to determine “where Pluto and its moons fit in with the other objects in the solar system, such as the inner rocky planets (Earth, Mars, Venus and Mercury) and the outer gas giants (Jupiter, Saturn, Uranus and Neptune).
On the 14th, New Horizons will be within 7,800 miles of Pluto’s surface. But at almost three billion miles from earth, data sent from the probe, travelling at the speed of light, will take more than four hours to reach us.
Thanks to the near-endless power of its plutonium engine, New Horizons will leave Pluto and delve farther still, into the heart of the Kuiper Belt, a region at the solar system’s outer limits made up of countless icy mini-worlds akin to Pluto.