Question

Earth is the only planet that is able to sustain life"". Give four reasons to substantiate this statement.

Answer 1

Explanation:

Earth is well equipped as a planet and ideally placed in our solar system and galaxy to support life as we know it. The product of some 4.6 billion years of cosmic construction, our planet is flush with life thanks to a fortuitous set of conditions.The planets orbiting other stars range from huge gas balls such as Jupiter, covered with raging storms, to extremely hot worlds that have oceans of boiling magma, to small rocky worlds that may be like our own.

Earth, described by astronomer Carl Sagan as a ‘mote of dust suspended in a sunbeam’, photographed by the Voyager 1 space probe at a distance of more than four billion miles in February 1990

Earth, described by astronomer Carl Sagan as a ‘mote of dust suspended in a sunbeam’, photographed by the Voyager 1 space probe at a distance of more than four billion miles in February 1990 © Wikicommons

We can’t find all the small planets yet, because they leave only a tiny signal for astronomers to spot, requiring long observation runs on large telescopes and dedicated space missions such as Nasa’s Transiting Exoplanet Survey Satellite. But the data we have accumulated suggests that at least every fifth star harbours a rocky planet at a distance from its star where liquid water could exist on the surface.

This distance, where it is not too hot and not too cold for liquid water, is called the “habitable” or “Goldilocks” zone. Astronomers are interested in worlds that orbit within that zone because liquid water is essential for life as we know it. It was exciting to be part of the team that, a few weeks ago, announced the discovery of one such planet, GJ 357d, and led the work on characterising it. The star it orbits, which lies in the constellation of Hydra, is 31 light years away — relatively close, given our galaxy’s 100,000-light-year diameter.

The challenge now is to refine our observations to the point where we can answer the question that fuels many people’s fascination with these worlds: do any of them actually harbour life?

Answer 2

Answer:

- Earth is at optimum distance from the sun.It is neither too far to get frozen, nor too close to get burnt.

- Earth has an atmosphere comprised of life giving gases like oxygen and carbon dioxide.

-  Earth is the only planet covered by 70% of water which is essential for life.

- The ozone layer in our atmosphere blocks the harmful rays from destroying life on earth.