Life on distant planets — and why they’re so glowy

Image copyright WHOI Image caption In 2002, Hungarian astronomer Gyorgy Tolnay looked out from a telescope on Mt. Majdali in the Alpes-Maritimes region of southern France and realised that a massive galaxy 20 million light years away was slightly out of alignment. This was the closest stars he’d ever seen to that galaxy.

Every two days or so an astronomer with a telescope scans the sky for visible light from distant planets or other worlds in order to gauge whether they could support a biology-encouraging biological activity.

This is known as looking for a planet

Or scanning the sky for brighter light than stars.

These observational targets are named targets.

Because of the way light bends in the vastness of space, a star has a feature known as a “disc”. That’s the name astronomers give to this brilliant, sun-like star that would be easy to spot on any planet – but planets often have other things in mind.

Image copyright Universe Imaging Foundation Image caption Investigator Jonas Stötzner looks for infrared light that had previously been hidden by the glare of gas. The planet orbiting one of these distant stars in this image looks significantly brighter than any other stars he’s seen.

On Earth, many stars possess a characteristic called a thin smog, which allows gases to be detected in the atmosphere of a star 10 times further away. Because of this, astronomers are sometimes able to infer that the gases are molecules, although they are not always specific molecules.

All of the planets in our Solar System have this signature as well.

Among the most intriguing are the dwarf planets like Pluto and Eris, which orbit closer to their parent stars than Neptune orbits the Sun. If an Earth-like planet existed in this region of space, it might be observed by looking for the chemical signature of an oxidant called osmium that was previously restricted to oxygen and hydrogen.

If osmium were present in the atmosphere of a distant planet, it would initially appear as a reddish light in the Universe that looks a bit like sunlight.

Image copyright Irwin Temkin Image caption The discovery of Jupiter’s 13 Galilean moons inspired Temkin to explore the Universe with spectrometers

The big question is where the planet would be.

Since gas flares are the main signs of heat and energy present in stars, the researchers first looked for obvious gas blazes associated with these stars.

On previous occasions, looking for this clue revealed an orbit too small, or another moon, and so the team searched for a planet beyond the giant stars.

Recently they looked for planetary orbits closer to the stars, and found several candidates – still within our own galaxy – that appeared as large as Earth.

These distant exoplanets also look a bit brighter than our own.

This brightness is because the moon in our sky is half a second larger than the Sun, and that also impacts how much light enters the planet from our side.

If this is a real world detection, it would be one of the first-ever definitive evidence for the existence of a planet.

Image copyright PA Image caption Finding exoplanets has become a major initiative for the European Southern Observatory

Many years ago, Hungarian astronomer Gyorgy Tolnay discovered that a massive galaxy 20 million light years away was slightly out of alignment with its stars.

This was the closest stars he’d ever seen to that galaxy.

Tolnay also discovered that a series of galaxies on the same astronomical plane was missing more than 50 dark holes – which leave no light even though there could be more than 100 on each of the galaxies.

He thought this was odd, because these galaxies are known to have two dozen stars on each side, indicating they are locked in a cycle of fading and brightening, and are best considered at one spot in space.

After years of searching for these dark holes, two surprising ones are discovered.

Tolnay still doesn’t understand why the gravitational force between the galaxies is more pronounced on one side than the other.

Now astronomers are asking what could be the source of these gravitational effects.

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