In a landmark finding in history, astronomers have reported discovering the most Earth-like planet outside our Solar System to date, a world that may have liquid oceans and thus life.
European scientists found the body, estimated to be 50 percent wider than our Earth, orbiting a so-called red dwarf star relatively close to Earth. The object is estimated to weigh as much as five Earths and would have more than twice Earth's surface area.
Other curious features of the newfound planet are that gravity at its surface would be around twice as strong as on Earth; and its year is just 13 Earth days long, as it completes one orbit about its sun in that time. It's 14 times closer to its star than we are to our Sun, but since its host star is smaller and cooler than the Sun, the planet nevertheless would lie in its habitable zone with suitable temperatures for liquid water. The host star, Gliese 581, is among the 100 closest stars to us, lying 20.5 light-years away in the constellation Libra, the 'Scales'.
In the 200th year since its discovery, asteroid Vesta (below), the brightest of all asteroids, makes one of its best showings ever. Vesta, is at opposition on 31 May and will be at 170 million km from the Earth, almost as low as it can get. This is a very favourable opposition with the asteroid nearly as bright as it can get. Vesta will be visible to the unaided eye from a dark site with no Moon in the sky. Star charts available on the internet can help find Vesta, which is in the constellation of Ophiuchus.
Other celestial attractions for this month are the meeting of Mercury and Saturn with the Moon. If you can catch sight of the very new crescent Moon on the evening of 17 May, then try looking for Mercury at the same height above the horizon, but three degrees to the left; the two objects will easily fit together into the field of view of a typical pair of binoculars.
In the early morning hours of 23 May, our own waxing crescent Moon will pass directly in front of Saturn. The planet will disappear behind the dark limb of the Moon and will reappear from behind the bright limb just after one hour. For the rest of the evening on 22 May, the Moon will appear very close to the left of Saturn.
May highlights:
The Sun is in the constellation of Aries at the start of May, moving into Taurus on the 14th.
Mercury is behind the Sun on 3 May but it makes its best evening appearance at the end of May, low in the west after sunset.
Venus rises higher and becomes more dazzling in the western sky as it crosses from Taurus into Gemini. On the evening of Saturday, 19 May, the crescent Moon itself will be just three degrees to the lower right of Venus.
Mars is still lurking low in the east before sunrise; it rises just over an hour before the Sun. It won't be possible to make any useful observations of it this month.
The giant planet Jupiter is in the non-Zodiacal constellation of Ophiuchus. At the start of May it's rising in the south-east at about midnight. By dawn Jupiter is in the south-western, just above the horizon.
Saturn, in Leo, is sinking a bit lower, is still nicely visible in the southwest during the early evening hours. On the night of 22-23 May, our own Moon, waxing crescent, will pass directly in front of Saturn.
