The Search for Exoplanets

The study of exoplanets is a relatively new field of research in astronomical studies. Only until 1995 was the first real exoplanet that orbits around an actual star discovered. Technology has been rapidly growing ever since and so has the number of exoplanets being discovered.

This essay is in the format of a scientific report that gives detailed information on exoplanets. It starts with a brief introduction of what exoplanets actually are accompanied by a brief history of the same. It then focuses on what scientists look for when they are searching for exoplanets. Accompanying this is also some detailed information on the methods used when searching for exoplanets. The essay then goes ahead to describe why it is important to study and search for exoplanets before it concludes.
Human beings have been evolving ever since the days of the early man. Learning new things, understanding new concepts and discovering the unknown has been the core of the whole process. They say the sky is the limit but in modern times that doesn’t seem to apply anymore. We have expanded our scope of research to infinite space. What is now known goes beyond the solar system and beyond our galaxy to places as far as one can possibly imagine? As some say, human evolution has been taken to the next level by some of the phenomena uncovered by space research and space exploration (Borde, 2003).

Human beings are generally very curious and inquisitive in nature. The idea to find planets that are similar to the earth is very old. However, due to the inadequate technology that was available, it remained only a dream until very recently. It was impossible to explore planets outside our solar system until 1995 when the concept of an exoplanet was born. The most basic definition of an exoplanet is a planet that is not within our solar system or one which doesn’t orbit around the sun. However, an absolute definition can be rather challenging since some of the vital characteristics it has to possess is an environment similar to earth’s and it can be giant or just terrestrial (Elu, 2011).

During the early 1990s a lot of effort was going into finding planets that orbit around ordinal stars. Astronomers had successfully used infrared observations of proto-solar systems to detect planets that orbited around pulsars, but they hadn’t found any planet around an ordinal star until the October of 1995. Two scientists, Didier Queloz and Michael Mayor discovered a Jupiter-size planet that is 20 times closer to its sun than we are to ours. The planet was named 51 Pegasi b after its star, ‘51 Pegasi’, it has a temperature of around 1000 degree Celsius and it orbits 51 Pegasi in just four days (Bbc.co.uk, 2011). Since then about 3440 exoplanets have been discovered and the research is still continuing.

The distance from the sun to the earth is 149.6 million kilometers (Pomme,2016). This is very far and yet it’s in our solar system. Exoplanets are found millions of miles away from the earth and our sun and thus taking their images can be very difficult. Scientists also require to record other important characteristics of these planets which can be very complicated at times. The good news is that today there are several methods that are available and one can use when detecting exoplanets. Scientists concentrate on certain characteristics or properties of the body under investigation and how it behaves in order to determine whether it is really an exoplanet.

The first thing that the scientists can do is to watch for a wobble. If a star has a planet revolving around it, the gravitational forces of the two may interact and at some point, it may cause the star to wobble or move a little bit. The details of the wobble are analyzed using the Doppler shift method to successfully determine whether an exoplanet actually exists around a wobbling star. Its size and other properties too can be determined. 664 planets have been discovered using this method (Han, 2014).

Secondly, scientists can search for shadows cast by the planet on a star. When a star is passing across a star it dims the light of the star considerably for a short period of time. Like for instance, Jupiter causes 1% dimming of light as it passes between the sun and an observer. This information is analyzed and the properties of the object causing the dimming can be known. This method alone has been used to discover two thousand, seven hundred and eighty-eight planets (Han, 2014).

The third method that can be used to observe planets outside our solar system is directly taking pictures. It’s quite hard bearing in mind how far these planets are. Scientists use shine blockers to reduce the glare of the star in question thus making it easier to have a view of the planets around it. They may use coronagraphs to block light before it reaches the telescope detector or they may use star shade blockers to block the stars light even before it gets into the telescope. The technology is still new but it has been used to discover forty-four planets (Han, 2014).

Wobbling can be analyzed not only by using the Doppler shift method but also by using a method known as astrometry. Precise optics are used to track stars and their wobbling motion. This method is very complex and it has successfully been used to discover only one star.

Also, scientists do observe the light that is being emitted from a star using gravity lens. Light from a distant star is bent and focused by gravity whenever it passes near a massive body such as a planet making it appear temporarily brighter, a phenomenon known as gravity microlensing (Penny, 2015). Detailed analysis of the phenomenon has helped astronomers discover fifty-three planets (Han, 2014).

The above are properties and characteristics of exoplanets that scientists can use in order to confirm their existence. However, there are so many other things about these planets that they still dig into. For instance, they do study and measure their atmospheres in order to determine what gases exist in their gaseous envelopes. With the modern technology, they do measure their surface temperatures, the size of their orbits, magnetic fields and even determine their colors. They have also found one exoplanet with an exomoon and another that leaves behind a trail of material as it vaporizes orbiting very close to its star and as technology advances more are expected to be discovered.

A lot of money, time and human resource are spent by the government and investors towards research on exoplanets each year and one might ask himself, is it really worth it? For one, it might be important because it helps us understand our own solar system. We may have really nice ideas of how planets form, but there are still aspects of planet formation we would like to know about. A good example is the discovery of a planet that looked like Jupiter by Keck that was orbiting a single star in a triplet system. This changed some perspectives that were previously held by scientists. The discovery was quite astonishing because, for one, it was previously believed that a planet could not survive such strong gravitational forces such as present in such a system and second in the current model of planet formation, gas giants are formed into the proto-planetary disc at the edge of the solar system and then later move inwards. However, this particular system suggests otherwise, two other stars circle the one at the middle beyond the planets orbit and the model does not necessarily provide a convincing explanation of how planets were formed.

The second importance of studying exoplanets is the possibility of finding other planets that can support life. There exist big incentives that there is a possibility of finding a planet that is like earth, one that exists within its stars habitable zone (Jenkins, 2015). The zone is defined by the temperature change as the distance from the star increases. In our solar system, only earth exists in this zone although there is a possibility that at some point in time mars was. The habitable zone is in the range from the star where a planet’s temperature allows liquid water bodies that are very essential for life. Scientists hope to stumble upon such an exoplanet someday.

With the increase in technology level more can be expected to be discovered on exoplanets and on astronomy in general. In the future NASA believes they will someday be able to send expeditions to these planets.