All About Space

Life within the Solar System?

Earth is the only planet we know of that hosts life, but which other worlds could one day surprise us?

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Venus

Type of world: Planet Minimum distance from Earth: 225 million kilometres

(139 million miles)

Venus is the hottest planet in our Solar System, so that should rule out the potential for life. But there is a theory that microbes could exist in the clouds, where temperatur­es are cooler. In fact, phosphine – a potential marker of life – has been observed in the clouds.

Mars

Type of world: Planet Minimum distance from Earth: 225 million kilometres

(139 million miles)

Mars has long been seen as a prime candidate for harbouring life because of its proximity and similarity to Earth. In reality the surface of Mars is unlikely to be hospitable to life today, but microorgan­isms could exist in ice or water within the planet’s subsurface.

Europa

Type of world: Moon Minimum distance from Earth: 780 million kilometres

(485 million miles) Cracks on the surface of Europa, one of Jupiter’s moons, as well as fluctuatio­ns in its magnetic field, have led scientists to believe there is a vast ocean beneath the surface. There is a possibilit­y that it could contain some form of life, if not in the water itself then in the upper ice layers.

Enceladus

Type of world: Moon Minimum distance from Earth: 1.272 billion kilometres

(745 million miles) Scientists believe that Saturn’s sixthlarge­st moon has the ingredient­s needed for life. Aside from a global ocean beneath its icy crust, hydrogen was discovered in the plumes erupting from the south pole, meaning there’s a source of chemical energy. It’s our greatest hope for a discovery.

Ceres

Type of world:

Dwarf planet

Minimum distance from Earth: 426 million kilometres

(265 million miles) Ceres, the largest object in the asteroid belt, has water, and it could be in liquid form, so there is a ferocious appetite to explore this celestial body further. If life is discovered it’s not likely to be anything more than small microbes, but that would nonetheles­s represent a major breakthrou­gh.

Titan

Type of world: Moon Minimum distance from Earth: 1.6 billion kilometres

(1 billion miles)

Saturn’s hazy moon has a subsurface ocean of liquid water. It also has lakes and rivers of liquid methane and ethane, as well as a weather system similar to Earth’s. Astronomer­s ponder how methane is finding its way into the atmosphere. If life exists, however, it may not be quite as we know it.

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