I’m Caitlin Hofmeister.
Welcome to SciShow Space News.
Let’s start by clearing up the gossip around an important discovery that was made last
week.
You might have heard that the Kepler space telescope captured evidence of an Earth-like
exoplanet 500 light-years away.
Well, Kepler did find something really important out there, but it was an Earth-sized planet,
which is an important distinction and still exciting news.
The planet, named Kepler-186f has a radius just 1.1 times the size of Earth's, and that’s
a big deal because until now we’ve had a hard time spotting exoplanets of this size.
Using a technique called the transit method, Kepler watched for the minute dimming that
happens when a planet passes between us and its star, blocking out a tiny bit of its light.
The smaller the planet the less light it blocks and the harder the dimming is to catch.
That’s why most of the planets we’ve seen have been at least 40 times larger than Earth.
But the discovery of Kepler-186f is heartening evidence that Earth-sized exoplanets are out
there.
The reason this world has been described as Earth-like is just because being around the
same size as Earth means it’s likely to have some similar characteristics.
For example, because of its size, astronomers think 186f might have gravitation similar
to Earth's and they also say there’s a very excellent chance that is has a rocky surface
and it also may have water.
Like Earth, 186f is in the so called habitable zone of its star meaning it’s just the right
distance from its star that water could exist there in a liquid state.
But that’s not to say that we know there’s water there, let alone that it’s liquid.
As we’ve talked about before, our own solar system proves that the habitable zone is just
a vague indicator about the possibility of water.
Venus, for instance, is in the Sun’s habitable zone but its atmosphere is too hot for liquid
water.
While on Mars, a weak magnetic field has allowed solar activity to strip away the atmosphere
making it too cold for liquid water.
Besides, Kepler-186f is different from Earth in one very important way – its star is
different.
Kepler-186 is a red dwarf which means it’s much older than our sun.
On one hand, that could be promising because it means life would have had a much longer
time to develop in its system.
But on the other hand, it’s much smaller and cooler than our sun, so Kepler-186f probably
only gets about 30% as much energy from it as we get from the Sun.
And speaking of the Sun, if you’re in eastern Australia, off the east coast of South Africa,
or in Antarctica for some reason, you may get to see an annular solar eclipse on Monday.
That means that for about half an hour the Moon will pass directly between the Earth
and the Sun, and the Moon’s apparent diameter will be smaller than the Sun's.
So when perfectly aligned, the Moon will block out all but a thin outer ring, or annulus,
of the Sun.
This ring will be visible beginning at around 5:48 coordinated universal time.
That’d be 3:48pm in Melbourne and Sydney.
Although the point of greatest eclipse will only be visible from Antarctica, so you should
probably just go there.
The next annular eclipse won’t occur until September 2016 so try to catch this one while
you can.
But remember, looking directly at the Sun will cause eye damage, so don’t try and
observe the eclipse directly.
And finally, here’s something you can marvel at safely - this awesome image captured by
the Hubble Space Telescope.
Using an exposure about 14 hours long, the image allows us to see features about a billion
times fainter than we can see with the unaided eye.
And it also happens to capture a particularly excellent example of gravitational lensing
which lets us see distant things that are otherwise hidden behind massive objects.
See, massive galaxies in our line of sight have enough gravity to bend light around them,
in the process, magnifying objects behind them much like a glass lens does.
In this image, a cluster of galaxies that looks like a small loop in the middle is magnifying
the light of a quasar as it’s falling into a black hole.
And this image is nine billion light years away meaning gravitational lensing has allowed
us to see back in time, through two-thirds the age of the universe.
Even the galaxies we’re using as lenses are really distant.
NASA says most of the objects you see here are five billion light-years away.
I hope that satisfies your curiosities for the week.
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