How do scientist know so much about planets which are millions of miles away?

Question

In the news this week there was a report of a new earth 2.5 light years away. How do they know what kind of atmosphere it has, what the land is like and what the size of it's sun is from such a distance?

Answer 1

They know the size of its sun by analyzing the light from that star. That will tell the temperature of the star. By knowing how far away it is, they can tell the size from this. They know the size of the planet by looking at how the star wobbles in response to the gravity of the planet. We do not know what the atmosphere of this planet is like. We do know it for other planets: if they go directly in front of their star, their atmosphere can be seen through the light from the star.

Answer 2

They can observe the 'wobble' of the star, caused by the gravity of the planet orbiting it. This tells them the strength of the gravity being exerted on it. Since the direction of the wobble depends on the position of the planet in its orbit, they can determine how quickly the planet orbits the star. This depends on the radius of the orbit, ie the distance of the planet from the star, which can thus be determined. If you know the distance of the planet, and the magnitude of the gravitational influence on the star, you can determine the mass of the planet. By knowing the distance from the star, and the type of star, you can calculate the temperature on the planet. (You know the type of star basically, from its colour and absolute magnitude). Knowing the planet's approximate temperature you can say whether water would be liquid there or not.
What is not known, is whether there is any water present, what kind of atmosphere it has, what its diameter is, or anything much beyond what I've already outlined. All the other information about it has been media speculation, based on nothing, purely to make the story more interesting for the mentally subnormal audience that all news programmes for some reason appear to believe they are broadcasting to.
incidentally, it was 25 light years, not 2.5. (There are no stars closer than 4.2 light years).

Answer 3

It's all done by measuring the radiation (light, infra-red, UV etc.) coming from the star it is orbiting. The intensity of the radiation 'wobbles' up and down minutely as the planet passes between it and us, detecting this wobble tells us roughly how big the planet is, roughly how fast it orbits it's sun, and from that we can work out roughly how massive it is.

The light can be split using a spectrometer, and the dark lines in the star's spectrum help us determine what it and the orbiting planet and it's atmosphere are made of.

Scientists also make an estimate of the size, conditions etc. of the planets based on our knowledge of our own solar system, i.e. huge planets tend to be gaseous giants, small planets tend to be rock etc.

Answer 4

They don't. You 're reading between the lines. All they know is that the planet has a mass 5 times the earth, is close in temperature and orbits it's small sun in 20 days or so. They measure the wobble of the star and can infer the mass and temperature is measured looking at infrared light. The planet may be a gas giant, it may have no atmosphere or it might be covered in sulfuric acid. That part is unknown.

ps - it's 20.5 light years away or 800,000 years by space shuttle

Answer 5

You can't spot them by looking through a telescope as they're too far away. The only way to identify extrasolar planets is to look for the effect they have on their parent star.

Spotting the cosmic clues

An orbiting planet will affect its parent star in two ways:

* The movement of the star
Stars revolve slowly around the centre of their galaxy in a smooth, elliptical orbit.

But if a star has planets around it, their combined gravity will yank the star out of its smooth orbit. This makes it wobble slightly as it cruises around its galactic path.

By measuring the size of the star's wobble, astronomers can work out the size of its planet, and how far it is from its parent star.


Normally, stars shine with a constant brightness. However, if a planet passes between you and a star, then the star dims as it passes by.

Measuring the changing brightness of a star can tell us whether there are planets orbiting around it.

For an alien planet to house life it must be:

* Close enough to its sun to receive enough energy

* Not so close to its sun that it's too hot for liquid water to exist

This region around a star is known as the 'habitable zone'.

Answer 6

Through spectroscopic techniques they can determine what elements, atoms and molecules are present in the atmosphere in a star. There is a temperature relation to the spectrum you see. You can then determin what type of star you are looking at and what mass it has. The bluer a star is the hotter it is. The hotter a star is the more massive it is. You can alos determin the mass of a star if it is in a binary system. You determin the period with which the stars revolve around their common center of gravity. You can then use keplers laws to calculate the combined mass of the system. You can use a similar technique to determin the mass of a planet around a star. You can see the star wobbling as the planet orbits. If you know the mass of the star you can find out the mass the planet would have to have to cause that tug. The period of the wobble is also the planets period.

Answer 7

It is actually 20.5 light years away. And they can tell a lot about a planet on how it influences the star that it revolves around. For instance the size the mass the distance away from the star.And for one thing , scientist have many peers that would discredit them if it were the right thing to do. Do you see anyone discrediting them yet? Maybe wont happen.

Answer 8

yes the new earth, firstly its sun is a dwaf star, meaning its coming to the end of its life, wich means the new earth is 10.000 million years infront of us (stars live 10.000 million years giv or take a few mill) so if there is life (wich i think is a massive poss) they will be so advanced and would be looking for a new habiterble planet to move to (earth), but i dont think goverment will tell us there is if they find it as you would not beleave some of the stuff that are paintented for 100 years, your question, we can find out by viwing the reflection its sun makes on the new earth and see in the reflection of light weather there is water rocks ect, our own ozone lyer reflects in our suns light, known as the northern light.

Answer 9

Photo spectrometry,all elements obs orb light at various different wave lengths.Observing a spectrum photograph will show a shadow caused by the absorption of certain frequencies due to the existence of it`s corresponding element.

Answer 10

There are several methods to learn different things. The light (and other waves) that an object emits tells us its temperature; the amount light bends around an object tells us its mass. Temperature and mass help determine what type of atmosphere is possible.