Tag Archives: Outer space

Radial Velocity method of finding an exo-planet

You might want to recollect some of the topics you have studied before going into this, if you haven’t don’t worry I will explain it all in this summary. Let us begin the journey………..

You might have studied about Doppler Effect in physics. Of course it deals with the sound from a moving object while listening from a stationary point. The same applies in the light spectrum too. If a light source is drawn away from an observer the most of the blue light in that spectrum will get scattered and the red light is all that remains in that spectrum. This is because the low wavelength of the blue light makes it to scatter when travelling through air molecules and the red light has a larger wavelength which mays it to travel longer distance without getting scattered.

We all know that stars and planets are bound together by a weak and a long range force called gravitational force of attraction. Each and every mass in space possess gravity. Depending upon its mass and density the gravitational magnitude will vary. If an object is lot denser it’s force of gravity will be huge, if its density is low the force of gravity will be low. That’s why extremely dense black holes possess inescapable gravitational force and it can even rip the space and time. We’ll talk about the black holes later.

So, you might ask what this has to do with the spotting of an exo-planet, here’s the reason why.

When a planet revolves around its host star its gravitational force affects the star’s axis of rotation, i.e. the star wobbles due to the gravitational force of the planet.


When the planet comes between the earth and the host star the host star is pulled towards earth for a fractional amount, this makes the light spectrum from the star to possess some blue light wavelength too and when the planet goes behind the star, the star gets pulled away from the earth and the starlight spectrum goes red. By detecting these variations in a starlight spectrum we can easily confirm that a planet definitely revolves around it. By using this method we can also find the mass and density of the planet revolving around it. Although this method can only be used for detecting large planets because only large planets have enough gravity to make the host star wobble along its rotational axis. Remaining ways to find an exo-planet will follow later.

Want to discover an exoplanet..? Then Hop on


Exo-plants or extraterrestrial planets are really exciting to find and hard to find. Do you really want to know how to detect and find an exo-planet, then tag along on the amazing journey of ways to find one.

The different ways are given below

  • Radial velocity
  • Transit method
  • Orbital light variations
  • Light variations due to relativistic beaming and ellipsoidal variations
  • Timing variations
  • Gravitational micro lensing
  • Direct imaging
  • Polarimetry
  • Astrometry
  • Auroral radio emissions
  • Modified interferometry

In this series of articles we will see about almost every method in detail. The first one will be out in minutes………. Just stay tuned…………

Say hello to the new Exo-planet hunter

img source : MIT Kavli Institute for Astrophysics and Space

Transiting Exoplanet Survey Satellite (TESS) is going to be next exoplanet detecting satellite which is set to be  launched in 2017 by NASA as announced by them in the first week of April month. The TESS, which will be the successor to the Kepler space telescope which bound to find out the Possible planet hosting neighboring stars.

Unlike Kepler, the TESS will find out most closest planet bearing stars. Until now the Kepler has been staring  3000 light years into the space in the direction of Cygnus constellation and it’s telescope’s detectors were programmed to target 150,000 possible planet hosting stars in that grid. So far it has discovered almost 22,500  possible planets in which most of them are found to be huge gas giants like Jupiter and some of them are super earths, Whose size is 2.5 times to 5 times the earth size and found to be terrestrial planets are not habitable planets of living organism to exist. Although approximately 51 earth-like planets has been found in the same grid. The first potentially habitable planet Kepler-22b was discovered in Dec 2011. It’s sensors are designed to measure the light blocked by a planet revolving around a star. By measuring the drop in the starlight the size of the planet can be found.

img Source : Wikipedia

The main disadvantage of the method is that we can’t measure the light dip when a earth size planets crosses a host star. The light variation will bee very small so that a sensor can detect it.

The Kepler mission is almost at it’s end, although NASA is trying to revive it’s full functionality, the hopes are very much slim. Next mission will be the TESS space telescope for detecting the nearest earth-like exoplanets within 6.5 light years in the vicinity of our solar system. It will be helpful for closely studying the exoplanets for it’s atmosphere composition, temperature and other vital parameters which are very important for the existence of life forms.

An Astrophysicist and a Kepler team member Natalie Bataha said that the early results from the Kepler indicated that the TESS won’t have to look very far to a world potentially like ours. So we may expect exciting discoveries after the mission is implemented. Its also uses the same transiting planet technique as Kepler, but unlike Kepler it scans the entire sky by using an array of wide-field cameras to scan roughly two million of the brightest and closest stars in our galactic vicinity. The main objective of this mission will be to find the closest earth-like habitable planets where liquid water can exist and life can flourish. The team hopes that TESS will find up to 1000 exoplanets in its first two years of deployment.

One thing for sure, ” there will be other organic lifeforms exist in other exoplanets and it’s discovery will not take much longer from now “……….

So what’s your say in this…………..

please feel free to leave comments, ask doubts and share your ideas……….