‘Goodnight’ Kepler

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One of the most popular mission of NASA, Kepler Space telescope has come to an end!

Kepler is named after the German Astronomer and Mathematician, Johannes Kepler. In the seventeenth century, Johannes Kepler put forward his laws of planetary motion. These are three laws describing the movement of a planet around the Sun.

Johannes Kepler, a German Astronomer and Mathematician known for his laws of planetary motion. Image taken from Wikipedia.


NASA launched Kepler on March 7, 2009.

Kepler’s Launch in 2009.
Source – Wikipedia

On the evening of November 15 (2018), NASA’s Kepler space telescope received its final set of commands to disconnect communications with Earth.

The “goodnight” commands finalize the spacecraft’s transition into retirement, which began on Oct. 30 with NASA’s announcement that Kepler had run out of fuel.

Kepler Spacecraft
Image Source – Wikipedia

It is coincidence that Kepler’s ‘goodnight’ was on the death anniversary of Johannes Kepler exactly after 388 years of Johannes Kepler’s death!

The spacecraft is now drifting in a safe orbit around the Sun 94 million miles away from Earth.

The data Kepler collected over the course of more than nine years in operation will be mined for exciting discoveries for many years to come.



NASA started the mission to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in the habitable zone, and determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets.

The mission also aimed to—

  • Determine the percentage of terrestrial and larger planets that are in or near the habitable zone of a wide variety of stars
  • Determine the distribution of sizes and shapes of the orbits of these planets
  • Estimate how many planets there are in multiple-star systems
  • Determine the variety of orbit sizes and planet reflectivities, sizes, masses and densities of short-period giant planets
  • Identify additional members of each discovered planetary system using other techniques
  • Determine the properties of those stars that harbor planetary systems.


When a planet crosses in front of its star as viewed by an observer, the event is called a ‘transit‘.

Planets block some light of the star according to its size, when the planet passes in front of the star, and this changes the brightness of the star.

Kepler used this method to detect different star systems and planets in the galaxy.


A Transit.
Source – NASA







  1. Chen, Rick. Kepler Space Telescope Bid ‘Goodnight’ With Final Set of Commands | NASA. Last Updated November 16, 2018. https://www.nasa.gov/feature/ames/kepler-space-telescope-bid-goodnight-with-final-set-of-commands (accessed November 17, 2018).
  2. Johnson, Michele, and Brian Dunbar. Mission overview | NASA. Last Updated October 31, 2018. https://www.nasa.gov/mission_pages/kepler/overview/index.html (accessed November 17, 2018).


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