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for the longest time

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space seemed like a big nearly empty

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place

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and we were really only familiar with

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our home

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earth

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but as we learned more

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we realized there was actually a lot out

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there including planets orbiting the sun

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and even other stars

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to get to these more distant worlds

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though it helps to start thinking of

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space as a bunch of nested bubbles

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our first bubble is a magnetosphere

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earth's invisible magnetic field that

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protects us from high energy particles

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and radiation from the sun

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allowing life as we know it to develop

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and thrive

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the next bubble

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just past the solar system

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is the heliosphere

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the edge of the sun's influence where

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the particles and fields of interstellar

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space take over

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the two voyager spacecraft have left

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this bubble and are our first

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interstellar spacecraft it took voyager

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1 35 years and it took voyager 2 41

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years to travel this far

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the next stop is our nearest stars

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the alpha centauri system at just over

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four light years away is close by cosmic

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standards

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but it would take either voyager about

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75 000 years to get there at current

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speeds

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we clearly need to use other tools to

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look for worlds that far away

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enter kepler a space telescope that

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radically changed our understanding of

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planets outside of our solar system also

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known as exoplanets

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in finding thousands of new planets

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kepler showed that there are more

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planets in our galaxy than there are

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stars

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but kepler looked at only a small

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fraction of the sky

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and many of the planets it discovered

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are too far away to study in much

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further detail

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and that brings us to tess

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our newest planet hunter the transiting

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exoplanet survey satellite works like

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kepler

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and over the next two years it will scan

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almost the entire sky

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by looking at closer and brighter stars

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tess will find and measure the sizes of

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dozens of small nearby planets best

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suited for detailed investigation by

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powerful telescopes on the ground and in

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space like the future james webb space

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telescope

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and by doing that

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we might finally begin to answer the

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question of whether earth is alone

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or

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our own

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small and rocky

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covered in oceans and dense clouds or

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even possibly