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The Goldilocks Zone: Earth-like Planets Outside our Solar System

Updated on September 13, 2011

The Goldilocks zone, also known as the habitable zone (HZ) is the region around a star in which Earth-like planets may be found.

The habitable zone is shown by the blue region on the diagram. The distance of the zone from the star depends on the star's mass, which is shown on the vertical axis of this diagram.
The habitable zone is shown by the blue region on the diagram. The distance of the zone from the star depends on the star's mass, which is shown on the vertical axis of this diagram. | Source

Find out more about the search for extra-solar planets by following this link!


To be habitable, at least by carbon-based life forms, a planet must contain liquid water on its surface. This only occurs for a narrow range of temperatures. The temperature of a planet is largely determined by its distance from the star that it orbits.

Goldilocks Planets Discovered so Far

HD 85512 b

This exciting new discovery is the best candidate for habitability yet. Discovered in August 2011, this planet, which is 3.6 times the size of Earth, orbits star HD 85512 in the constellation Vela.

This planet is slightly warmer than Earth, at around 30 to 50 degrees Celsius. If it has a suitable atmosphere, with sufficient cloud cover to shield it from the star's harsh rays, it could be a suitable environment for extra-terrestrial life to develop.

Read more about HD 88512 b

Gliese 581 d

Gliese 581 is a red dwarf star located in the Libra constellation, approximately 20 light years from Earth. The planet Gliese 581 d was discovered in 2009 to be in the star's habitable zone. It is located towards the outer edge of the Goldilocks zone, so it may be slightly too cold to provide an environment in which life can thrive. In 2010, astronomers reported the possibility of a second planet located in the middle of this star's habitable zone. However, this has not yet been confirmed.

Could HD85512b or one of the planets around Gliese 581 be Earth-like?
Could HD85512b or one of the planets around Gliese 581 be Earth-like?


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    • zzron profile image

      zzron 5 years ago from Houston, TX.

      Cool hub, great info!

    • profile image

      JJ 6 years ago

      It was awesome I learned so much :)

    • Spirit Whisperer profile image

      Xavier Nathan 6 years ago from Isle of Man

      Wherever we look for something we find it. Doesn't this say something about the act of looking?

      Thank you for another interesting hub.

    • floating mind profile image

      floating mind 6 years ago from Chicago, Illinois

      It's just exciting that other planets out there have the potential to support life. I am sure that someday, such a planet will be confirmed to have the ability to support human life. Then, all that will be needed is the development of the technologies it will take to get humans there and back.

    • melpor profile image

      Melvin Porter 6 years ago from New Jersey, USA

      Topquark, good hub. Planets in the goldilock zone are not necessarily good candidates for complex life. For Giliese 581 is probably Earth-like but there are a couple of problems here. The planet around such a star and this close to it may be in tidal lock where one side is always facing the star and is very hot and the other side is facing away making it extremely cold on that side. The other problem is red dwarf stars flare a lot, ejecting massive flares and energized particles toward the planet. In most cases the planet would probably have lost it atmosphere under such extreme conditions. On the other hand if the planet managed to maintain its atmosphere; there may be simple, microscopic organisms on this planet.

      The other planet HD 85512 b is a highly potential planet for life to exist assuming the planet's cloud cover is not retaining or block to much of the light from the star. Since it sits on the edge of the habitable zone almost similar to where Venus sits in our habitable zone it may be a greenhouse problem there. There may be some life similar to our plant life and microorganisms here but again complex, intelligent life may not exist there.

      Just because a planet is in the habitable zone there are still many variables to consider for life to exist on these other planets and hopefully they will evolve into complex, intelligent organisms.

    • vocalcoach profile image

      Audrey Hunt 6 years ago from Nashville Tn.

      First, allow me to thank you for leaving so many uplifting comments on my recent hub "teaching children to Become Champions". I am so gratefull to you.

      I enjoyed reading this informative hub by you. I had not understood the " goldilocks Zone" until now. I am always interested in learning more about planets and this article provides that for me. Voted up, useful, interesting. I am a fan!

    • VENZKHVAM profile image

      VENZKHVAM 6 years ago from Milk way galaxy, trying to find a more adventurous place in another galaxy with my great followers

      I think that it will take another 50 years for some concrete evidence on a friendly planet where we can plan our journey to see some creatures. i pray to god for that.

      voted up

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      ruffridyer 6 years ago from Dayton, ohio

      They only found 2 planets in the goldilocks grid so far? They need to keep looking.