The dramatic announcement this week of the discovery of a small cluster of seven planets attached to a star just 40 light years away – a near neighbour – comes appropriately just weeks after the publication of a surprising, lost Winston Churchill manuscript, an 11-page essay, “Are We Alone in the Universe?” That question is not, nor should it ever have been, the preserve of cranks and eccentric scientists. This week we took a significant step towards answering it.
The seven Earth-size planets orbit a red, dwarf star, Trappist-1, about 12 times smaller than our sun. And at least three of them, the fourth, fifth and sixth planets out, are in temperate zones where liquid water may exist.
Due to the relative proximity of this remarkable planetary system, the first so far sighted, ground-based telescopes and the Hubble Space Telescope may be able to determine if water, oxygen, ozone, methane and carbon dioxide are to be found on them. These are key indicators that chances of finding some kind of life (as we know it) are very high. Such findings "would tell us there is life with 99 per cent confidence", says Michaël Gillon from the University of Liège in Belgium who led the search.
Until the last few years, scientists looking for life elsewhere in the galaxy have focused on finding Earth-size planets around sun-like stars – 3,400 “exoplanets” outside our solar system have so far been recorded – and the discovery of planets attached to a smaller, cool, red dwarf, the most common star, should significantly expand and open up the search for extraterrestrial life .
And while we're talking planetary news, friends of Pluto will be interested to hear that Nasa scientists want its unfortunate 2006 relegation to "dwarf planet" status rescinded. Their proposal to the International Astronomical Union is that a "planet" should be defined, in layman's language, as simply "round objects in space that are smaller than stars". Pluto's return to league one, full-planetary status would also see some 100 objects in our solar system similarly promoted, including the Moon.