Almost 25 years have passed since the discovery of the first exoplanet – that is, a planet outside our solar system. Today, we know of several thousand of them. ‘It’s difficult to put into words how exciting this is’, says researcher Andreas Johnsson. ‘We’re actually talking about whole new worlds.’
The first confirmed observation of an exoplanet occurred in 1995. Since then a lot has happened. When Time magazine recently compiled a list of the 100 most influential people right now, three of them were researchers linked with efforts to discover exoplanets.
‘The first that were found were gas giants several times larger than Jupiter, but in recent years we have found more and more planets made of rock like Earth’, says physical geographer Andreas Johnsson.
He has taken his research domain beyond our planet’s boundaries and is studying the landscape and climate of the planet Mars. His primary focus has been on the water on our neighbouring planet. Currently, he is working with measurements made on a certain type of landform where the earth-layer has slowly moved down the hillsides on Svalbard. The formations are virtually identical to formations that have been found on Mars.
‘How material moves down the slopes on Mars has long been unclear. By comparing results of studies we’ve done on Svalbard, we’ve seen that it’s probably due to the fact that the ground thawed and froze again and again successively on Mars. This is another sign that in the past there has been much more liquid water in the soil on Mars. These formations could not have come into being otherwise.’
Although there are interesting worlds to study in our own solar system, Andreas maintains that the research on exoplanets provides an even broader perspective on our place in the universe. The distant solar systems where exoplanets exist and how they differ in regard to how our own solar system looks can give us greater understanding of how our solar system formed. Our own solar system also gives us tools to evaluate new exoplanetary systems.
‘In the astronomical context, this can be a matter of small nuances. Such as that our planet is in the habitable zone, where liquid water can exist and life can emerge, whereas one of our neighbours, Venus, is a blast furnace and our other neighbour, Mars, is a freezer. Knowledge of our own solar system’s planets allows us to better study new exoplanets.’
The fact that researchers are discovering so many exoplanets right now is due to improved instrumentation, which has opened up new opportunities. A major contributing factor is the Kepler Telescope, which was launched in 2009 and has discovered more than a thousand exoplanets.
‘The Kepler Telescope is so powerful that we are discovering planets almost wherever we aim it.’
Because planets reflect so little light, most exoplanets are discovered by indirect methods. One such approach is to observe how there is a slight reduction in a star’s brightness when a planet moves in front of its parent star. Even so, researchers can already say something about the planets that have been found, including the distance from the star they orbit, the planetary mass and even what the environment of the planets may look like.
‘This is a fantastic area of research. It’s very stimulating to imagine what they look like and being able to send instruments there or even go there. As a physical geographer, I can’t help thinking about all the fascinating landscapes to explore – alien landscapes that all relate a unique history. The thought is staggering.