What is CHEOPS? | An European space agency mission

Introduction

CHEOPS stands for Characterising Exoplanets Satellite & it is an European Space Agency mission to study about the various aspects of exoplanets(outside our solar system) like their density,formation etc. It is expected to launch in October or November 2019 or may be early 2020. I will discuss everything in detail in the coming blogs but in this one i will only discuss about exoplanets & different methods used for the discovery of exoplanets over the years.

Exoplanets

One of the most common question from from last one-two centuries is "Are we alone in this universe? OR do aliens really exist?" & this question is one of the main reasons behind our curiosity in space exploration & in 21st century we have developed some extraordinary technology to learn more about our universe, recent news about the first image of black hole is one of the biggest examples of how far we have come across.

1. Searching for exoplanets began in the mid 20th century, first unambiguous discovery of an exoplanet orbiting around a star like our very own sun played a greater role in changing our perspective towards our solar system.
2. That exoplanet was named 51 Pegasi b and it was discovered on 6 October 1995. It was found orbiting it's host star in just a span of over 4 days.
3. As of 2019 we have nearly discovered about 4000 exoplanets with different situations like planets orbiting around two stars, these type of discoveries usually help us to break thoughts which exist in our mind like a planet always orbits around a single star & other different myths.
4. Studying these exoplanets will help us learn about how these systems formed & evolved over the years, it may also help to answer whether life exists on other planets like it exists on earth?

Discovery of exoplanets using various methods

Radial velocity method

The other name of this method is Doppler Spectroscopy, in simple words it says that if a body revolves around it's host star then the host star also moves in a certain path that may be circle or elliptical due to the gravitational & other forces effect over it by the body revolving around it.

• So when the star moves towards the observer which are humans from earth then the spectrum shifts towards slightly blue & when it goes away from the observer spectrum shifts towards red.
• This process may seem easy but it is very difficult to track the position of star due to various phenomenons but our technology advancement over the years have created such high quality spectrographs  which are very sensitive & are able to detect even small changes in the position of the star.
• Exoplanet 51 Pegasi b was also discovered by this method by a ground based observatory by spotting wobbles in it's star motion.

Transit photometry

This method is used to discover exoplanets by detecting a planet moving around a star & our planet earth, the passage of a planet between a star & earth is called "Transit".

 Here we basically deal with the dip in starlight a/c to observer's viewpoint, if a regular dimming of starlight occurs at regular intervals of time slots it is confirmed that there may be a planet.

 A small planet transiting a large star will create only a slight dimming, while a large planet transiting a small star will have a more noticeable effect.

Direct imaging method

In this method we measure the light from exoplanet itself, it can become difficult or the light can get lost somewhere in the glare of much brighter next star but with advancements in technology it has become possible for us to cancel out the glare of star & around 40 planets have been discovered from this technique.

Other techniques are micro lensing  & astrometry but these techniques are not used so much widely.

NOTE:-  Hey everyone i am trying to provide every single detail of this mission so it will be difficult for me to complete whole data in this single article so i am dividing every single information regarding this mission into different articles, so coming blogs will be related to this mission & i will provide link of next article in the end of each article so that it becomes easier for you to read about this mission.

Peace☮