Exploring the
Diversity of
Extrasolar Planets
New worlds around distant stars
Over 6000 extrasolar planets have already been discovered and the number is growing! But how do we manage to track down these fascinating objects over such immense distances? What have we discovered so far? Are exoplanets so different from our own?
Let’s take a look at our solar system: What is a planet?
A planet is a celestial body that orbits a star and is illuminated by it. It does not produce any light itself, but only reflects light from the star.
There are eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. They consist mainly of rock or gas. Some are orbited by moons.
Our solar system with its eight planets. IAU / Martin Kornmesser
They are fascinating objects in the universe that help us to learn more about the formation and development of the solar system.
Now let’s take a look outside: What is an extrasolar planet?
An exoplanet is a planet that is located outside our solar system and orbits a star other than the sun.
How do such planets form and develop?
This is what exoplanet research is trying to answer.
Exoplanet diversity. SPP 1992 / N. Barmann
They exhibit a variety of properties that we are not familiar with from our solar system, be it their size, orbital period and orbit or temperatures that melt any rock. A few examples:
GJ 367 - a planet that orbits the star in just eight hours.
With half the mass of the Earth, the newly discovered planet is one of the lightest of the almost 5,000 exoplanets known today. With an impressive orbital speed of less than 8 hours, GJ 367 b belongs to the class of ‘fast travellers’.
With a diameter of just over 9,000 kilometres, GJ 367 b is slightly larger than Mars. From the determination of its radius and mass, it can be categorised as a rocky planet.
GJ 367 b SPP 1992 / Patricia Klein
The distance of just under 31 light years from Earth is ideal for further investigations. Above all, to study how rocky planets like Earth form and evolve.
The new exoplanet’s host star, a red dwarf called GJ 367, is only about half the size of the sun. This was favourable for the discovery, as the transit signal of the orbiting planet was particularly strong.
The results were published in the journal ‘Science’ on 2 December 2021.
Here you can find an article by DLR.
Kepler-90 - a shrunken planetary system.
Eight planets orbit around the star Kepler-90. Similar to our solar system, there are small planets inside and larger ones outside. However, the entire system would not extend beyond the Earth’s orbit.
Kepler-90-System / NASA
The distance of just under 31 light years from Earth is ideal for further investigations. Above all, to study how rocky planets like Earth form and evolve.
The new exoplanet’s host star, a red dwarf called GJ 367, is only about half the size of the sun. This was favourable for the discovery, as the transit signal of the orbiting planet was particularly strong.
The results were published in the journal ‘Science’ on 2 December 2021.
Here you can find an article by DLR.
Trappist-1 - six rocky planets around a dwarf star
Six rocky planets orbit the dwarf star Trappist-1, three of them move in the star’s life-friendly zone.
TRAPPIST-1 System / The Planetary Society
Exoplanets have greatly expanded our understanding of the universe and revealed the possibility of other habitable planets beyond our solar system. It is an exciting and rapidly evolving field with new discoveries and insights being made all the time!
In the info carousel below you will find a selection of exciting articles. Click here for an overview of all articles.
The beginnings of exoplanet exploration
What hurdles had to be overcome on the the path to the discovery of the first extrasolar planets?
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Vera C. Rubin Observatory
How will this telescope revolutionise the field of astronomy and our knowledge of the universe?
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Thüringer Landessternwarte Tautenburg
How does this observatory contribute to the discovery and exploration of extrasolar planets?
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Historical overview
What hurdles had to be overcome on the the path to the discovery of the first extrasolar planets?
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Astrometry
What can determining the exact position of a star tell us about a possible planet?
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Direct Imaging
Why is it so difficult to see an exoplanet directly, even with powerful telescopes?
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Gravitational lensing
How can Einstein’s theory of relativity help to find planets that are otherwise undetectable?
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Transit method
How can measuring the brightness of a host star reveal the existence of a planet?
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Radial velocity method
How does an exoplanet interact with its star and how can we use this?
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Jupiter-sized planets
Are all gas giants similar to Jupiter or Saturn? What can we learn from these exoplanets?
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Neptune-sized planets
Why are there so few medium-sized exoplanets close to their host star?
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