There are certain questions we ask ourselves that we immediately regret asking. And yet, we can't stop thinking about them until we have the answer. A case in point? What would happen if the Earth stopped revolving around the Sun? Would it plunge into an endless journey to the farthest reaches of the galaxy? What would happen to life on Earth as we know it?
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A subtle balance
Seen from a satellite image, the Earth appears to be 'magically' suspended in space. But any astronomy buff knows that what keeps our planet in space in this way is due to a perfect balance between the gravitational force exerted on it by the Sun and the Earth's inertia, its own orbital motion. One of Newton's famous theories. It's not magic, it's simply physics. In short, the Earth and Sun seem to be dancing a tango, where forces attract and repel each other in perpetual motion.
Can external forces disrupt this balance?
For the subtle Earth-Sun balance to be altered, a change would have to occur. The Sun, for example, could lose its gravitational force. But for this to be possible, it would have to lose mass; the attraction an object exerts being closely linked to its mass.
Scientists have already studied this future mass reduction. It's not expected until the Sun becomes a red giant, the process that initiates the death of a star. And the death of our beloved star is not expected for another 5 billion years. So let's not dwell on that for now.
An asteroid? Could an asteroid be powerful enough to alter the Earth's orbital speed? The experts' answer is pretty explicit:
An object big enough to alter the Earth's orbit is also big enough to destroy it completely!
In other words, we wouldn't have time to witness the Earth's long drift towards the Sun.
An exceptional case
Okay, we can see where you're coming from; despite all the scientific answers, you're thinking that, despite everything, it's likely, 'as if by chance', that a sufficiently large celestial body could modify the Earth's inertia, but without destroying the planet. Just imagine. Scientists familiar with our non-scientific way of thinking have had fun imagining this improbable hypothesis. The answer is clear. We'd have barely a month to survive. With the Earth inexorably drawn towards the Sun, temperatures would rise ever faster, taking all traces of life with them.
This article has been translated from Gentside FR.
Phys.org: Earth's orbit around the sun
Les Echos: La mort du Soleil comme si vous y étiez
BBC Science Focus: Could an asteroid knock Earth out of its orbit?
Business Insider: What if the Earth stopped orbiting the Sun?