For millennia, humans have asked whether we are alone in the universe, yet the discovery of aliens still eludes us.
But if extraterrestrials do exist, scientists have found a promising location for where they could be hiding.
Researchers from the University of Oxford have discovered an exoplanet dubbed HD 20794 d that could have the right conditions for life.
More than six times as massive as Earth, scientists are describing it as a ‘super Earth’.
It is located in the Eridanus constellation and is in the habitable zone of its star, meaning liquid water – and therefore life – could potentially exist.
Best of all, it’s just 19.7 light-years away from Earth.
This raises the tantalizing possibility that we could snap pictures of any aliens lurking there.
‘Excitingly, its proximity with us – only 20 light-years – means there is hope for future space missions to obtain an image of it,’ said Dr Michael Cretignier, who first spotted signs of the planet in 2022.
HD 20794 d was found using the HARPS (High Accuracy Radial Velocity Planet Searcher) spectrograph at the La Silla Observatory in Chile.
Described as one of the most successful ever planet finders, HARPS spends most nights monitoring stars for signals that indicate the presence of ‘exoplanets’ – planets outside of our solar system.
It uses a planet-detecting method called radial velocity, also known as the wobble or Doppler method, which can detect ‘wobbles’ in a star caused by the gravitational pull of an orbiting planet.
Using HARPS, Dr Cretignier spotted distinct, periodic shifts in the spectrum of light emitted by host star HD 20794, which he thought could have been caused by the gravitational pull of a nearby planet.
But due to the faintness of the signal, it was not clear whether this was caused by a planet or due to background ‘noise’ or a subtle instrumental error.
To verify the signal, an international team analysed precise measurements recorded over two decades by HARPS and its successor ESPRESSO, also in Chile.
By combining the results from the two instruments, the discovery was finally confirmed – a ‘relief’ according to Dr Cretignier because the original signal was at the edge of the spectrograph’s detection limit.
The discovery, detailed in a new study published in Astronomy & Astrophysics,also relied on data from NASA’s Transiting Exoplanet Survey Satellite (TESS).
Dr Cretignier and colleagues know HD 20794 d has a mass six times that of Earth, but as yet they do not know the diameter.
‘The method we are using only provides the distance to the star (the orbital period) and the minimum mass of the planet and not the radius,’ Dr Cretignier told MailOnline.
Although the planet is located in the system’s habitable zone, it is too early to say whether it could host life.
‘It’s important to remember that having a planet in the habitable zone is not sufficient at all to have life on it,’ he added.
‘Both Mars and Venus are inside the habitable zone of the sun, but I highly don’t recommend you to go there on holiday.’
More questions will have to be answered about the planet first, such as whether it has water on it and if it has an atmosphere, according to the expert.
‘The checklist is still long and we have decades of work in front of us,’ Dr Cretignier told MailOnline.
Unlike most planets, HD 20794 d’s orbit around its star is ‘elliptical’ – elongated and not perfectly circular.
Its distance from its star changes significantly, causing the planet to move from the outer edge of the habitable zone to the inner edge throughout its year.
The star is ‘a naked-eye star’, meaning you could even observe it if you are looking the sky in the south hemisphere, Dr Cretignier added.
Ultimately, the discovery could eventually give us the first signs of life outside our solar system – although there are many other promising exoplanet candidates.
‘Such a target will be among the primary target list of future space missions with such a purpose that will be on sky the next decade,’ Dr Cretignier said.
Already, NASA has a webpage dedicated to an exoplanet called ‘HD 20794 d’, which was discovered in 2011.
Dr Cretignier points out that this planet has an outdated name and is actually a different planet in the same system – HD 20794 c.
The HD 20794 star has three known planets orbiting around it – but there could potentially be more out there waiting to be found.
The whole system is 19.7 light years away, which, although relatively close to us in the universe is ‘desperately out of reach’.
‘On the scale of the universe, this is our neighbourhood,’ Dr Cretignier said.
‘Such is the paradox of the universe – it can be observed, not visited.’
NASA CONFIRMS THERE ARE MORE THAN 5,000 PLANETS BEYOND OUR SOLAR SYSTEM
NASA has confirmed that there are more than 5,000 known planets outside our solar system, known as exoplanets.
As of January 28, 2025, there are 5,830 confirmed exoplanets, according to NASA’s online exoplanet archive.
The total reached a milestone of 5,800 in early 2022.
Exoplanets found so far include small, rocky worlds like Earth, gas giants many times larger than Jupiter, and ‘hot Jupiters’ in scorchingly close orbits around their stars.
However, NASA stresses that only ‘a tiny fraction’ of all the planets in the Milky Way galaxy alone have been found.
The majority of exoplanets are gaseous, like Jupiter or Neptune, rather than terrestrial, according to NASA’s online database.
Most exoplanets are found by measuring the dimming of a star that happens to have a planet pass in front of it, called the transit method.
Another way to detect exoplanets, called the Doppler method, measures the ‘wobbling’ of stars due to the gravitational pull of orbiting planets.
