Hot Jupiters

63 light years from Earth a planet that looks like a big blue marble is being watched closely by astronomers. While the colour blue is often associated with feelings of calmness and stability, this particular world is anything but peaceful. 

On this planet daytime temperatures reach almost 1000 degrees Celsius and 7000 kilometre-per-hour winds howl across its surface. And researchers are pretty sure that gentle blue colour is a product of the hot molten glass that rains sideways on the planet!

This “blue marble,” called HD 189733b, is just one of the ever-increasing numbers of hot Jupiter planets being discovered by scientists as they search the universe for habitable planets. 

Planets in our solar system differ in numerous ways but there are two basic properties that can tell us a lot about them; their size and their orbit. A planet’s size determines if it has an atmosphere that can support life. A planet’s orbit, or how it circles its star, affects the temperature on its surface and whether there could be water there.

A planet that could support life has to be just the right size. Too small (less than 80 per cent of Earth’s diameter) and it doesn’t have the gravity to hold onto a life-sustaining atmosphere, too big (over twice Earth’s size) and it turns into a gas giant like Jupiter and Saturn. Jupiter, for example, is ten times bigger than Earth and 300 times heavier!

‘Hot Jupiters’ get their name because they are large and made of gas like Jupiter and they orbit their sun-like stars very closely, which raises their surface temperature to an extremely high level.

Fast fact: Gravity on hot jupiters can cause tidal forces to stretch planets into unusual shapes. WASP-12b is twenty times the size of Earth and shaped like an egg.

Hot jupiters are tidally locked which means that the same side always faces the sun. This means that on one side of the planet it is always a sunny day while the other exists in a permanently dark nighttime.

Hot jupiters orbit their suns at a much faster rate than Earth does its sun, completing the circuit in a few days or weeks as opposed to the year it takes Earth. That would mean a year on such a planet could only be a few days here.

Fast fact: Kepler-7B is a hot jupiter that is 50 per cent larger than Jupiter but half Jupiter’s mass which means it has a similar density to Styrofoam. It could actually float on water!

While we can’t see a hot Jupiter with the naked eye there are some super telescopes which can see them indirectly. Telescopes on space craft have also been able to feed scientists information on these fascinating worlds.

So far NASA has confirmed the existence of over 4000 exoplanets (planets outside our solar system) and around ten per cent of them are considered hot jupiters.

Article originally published in Brainspace Magazine

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