![Illustration of life forms on a hypothetical planet with a slightly lower mass than the Earth. It has shallow seas and extreme tides due to its large moon (thin crescent at left). The vegetation is translucent which allows the light to shine through, so it seems to be glowing, due to it being backlit in this image.](https://images.newscientist.com/wp-content/uploads/2024/05/03142247/SEI_202002983.jpg?width=1200)
The amazing differences we may find on other planets highlight the basic difficulty in defining life
RICHARD BIZLEY/SCIENCE PHOTO LIBRARY
Alien Earths
Lisa Kaltenegger (Allen Lane (UK) St. Martin’s Press (US))
A planet where a year lasts just one week due to it whizzing around its star 70 times quicker than the fastest fighter jet. A scorched, Earth-sized world, with two suns, where rocks melt into lava, evaporate and fall as rain. Planets with surfaces covered in vast, deep oceans. Others where their sun never sets, unless you travel to the distant reaches of their…