‘Habitable’ planet discovered orbiting distant star
A planet called Kepler-22b is the strongest known candidate for extraterrestrial life, astronomers have confirmed. But would finding ET really be such good news?
Even through the most powerful telescopes on Earth, and one in space, the planet known only as Kepler-22b shows up as nothing more than a flicker; a tiny shadow passing across the face of a distant star.
But for astronomers, that tiny flicker is a huge milestone in mankind’s scientific exploration of the universe. Why? Because Kepler-22b is now officially the most habitable-looking planet ever discovered.
The announcement at a special conference on the discoveries of the Kepler space telescope (after which the planet is named) is enormously exciting for alien-hunters. Unlike most ‘exoplanets’ discovered so far, Kepler-22b is in the same general size bracket as Earth. It has a similar orbital year, and its star is only a little less bright than our Sun.
Most importantly, the planet lies within its system’s habitable zone – the area in which liquid water, crucial for life, can naturally exist. In fact, it has an estimated surface temperature of 22 degrees C – the same as a fine Spring day.
And Kepler-22b is just the first. The existence of nine more Earth-sized exoplanets within habitable zones is likely to be confirmed in the near future.
Will any of them turn out to house alien life? Scientists are refusing to get overexcited. After all, they point out, Mars and Venus are both within the habitable zone of our Sun, and both, as far as we can tell, are entirely barren.
On the other hand, the Kepler telescope is scanning only a tiny fraction of our galaxy and has already discovered more Earth-like planets than many thought possible. That means that in total there could be many millions of places where life could thrive.
And, immediately after the Kepler announcement, scientists at SETI, the US agency which searches for intelligent life, announced that they were reactivating their specialised radio-telescopes to scan the new exoplanets for signs of civilisation.
Should we be so eager in our hunt for aliens? Many of the scientists doing the looking are driven by optimistic visions of minds meeting across the stars. What could we learn, they fantasise quietly, from alien cultures and extraterrestrial technology? What wonders of the universe might be revealed if it turned out that humanity was not alone?
But some fear this could all end badly for Earth. Aliens could be monstrous, or carry deadly diseases. They might not notice us at all and destroy us by accident. And there is a worse possibility: evolution – on any planet – produces ruthless, intelligent creatures that dominate and exploit their environments and cause mass-extinctions among ‘lesser’ species. In other words, intelligent aliens are likely to be just like we are – and that thought, some argue, should make us very afraid.
- Is humanity alone in the universe? What else, if anything, do you think might be out there?
- If two human-like civilisations met in space, do you think the result would be peace or war?
- Write a short science fiction story based on the first meeting between humans and aliens. How do you think it would go?
- What does a planet need in order to be suitable for life? Make a provisional list. The real list is longer than you might think.
Some People Say...
“If we meet aliens it is the aliens who should be afraid.”
What do you think?
Q & A
- So Kepler-22b is one of many candidates for possible life?
- One of probably millions in our galaxy alone. That doesn’t necessarily mean there’s any life out there though.
- Why not?
- At the moment, no one even really understands how life came to exist in the first place. It is a big leap from inorganic chemicals to even the simplest kind of living being. Life could be something that happens in all places where conditions are right – or something that happens only be the most unlikely chance.
- Can’t be that unlikely – it happened on Earth!
- Earth may be the only place it has happened in all the trillions of star systems in all the billions of galaxies in the universe. Of course, humans are only around in the one case where life has gone right – not vast number of cases in which it has gone wrong.
- Exoplanets like Kepler-22b are too small and too far away to see directly, even with the most powerful telescopes. Astronomers detect them by observing the tiny variations in light coming from a distant star which are caused when a planet passes between that star and the Earth.
- Kepler space telescope
- The Kepler spacecraft was launched into Earth orbit in 2009. Its powerful telescope is performing a detailed scan of a narrow region of the galaxy in order to try to find exoplanets which might host intelligent life.
- A planet orbiting a star other than our Sun. We are only just beginning to be able to detect exoplanets. The existence of the first exoplanet ever detected was only confirmed as recently as 2003.
- Specialised radio-telescopes
- SETI scientists scan the universe for life by listening in to various radio frequencies on which alien civilisations might be broadcasting. Aliens could detect life on Earth this way too, picking up our telephone calls and TV stations.
- Carry deadly diseases
- When Europeans first arrived in the Americas, relations with indigenous tribes were not always unfriendly. However, Europeans brought diseases like smallpox across the Atlantic. Indians, who had no natural immunity, died in millions.