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Astronomers   are constantly searching the night sky for   evidence of new and amazing  things in the universe.   Like a flash of light, a burst of particles,  or a ripple in the fabric of space.   But sometimes, the most remarkable  finding is… nothing at all.   In fact, recently, an especially  surprising bit of nothing was the key to   helping astronomers realize that they  were looking at something they had   never seen before: a planet that had  survived its star’s destruction intact.   This week, in the journal Nature, astronomers  published their discovery of a planet   the size of Jupiter orbiting the remains  of a star that was once like the Sun.   Now, before these astronomers zeroed  in on this particular “nothing”   that led to this discovery,  they did see something.   Back in 2010, researchers saw an  ordinary star suddenly brighten.   That can happen for a few  reasons, but in this case,   it was caused by an effect  called gravitational lensing.   Gravitational lensing happens  because of the way mass bends space.   As light passes through the warped space  around a massive object, it curves.   And if things line up just right, that  light can be focused toward Earth   just like how a glasses lens  focuses light towards your eye.   The sudden brightening of the star  astronomers observed in 2010 was caused by   a small gravitational lens, known as a  micro lens, created by an unknown object.   It was focusing the star’s light toward  Earth as the two objects lined up.   But in 2015, astronomers turned the powerful  Keck telescope to this spot in the sky…   and where the lensing object should  have been, they found nothing.   The same thing happened in 2016 and 2018.

That was odd, considering the object   was only 6500 light-years away,

which was well within Keck’s range.   So the fact that astronomers  saw nothing meant that   whatever was out there was extremely dim. Way too dim to be any ordinary star.   Various aspects of the gravitational lens  ruled out the possibility that it was   a remnant of a massive star, like  a neutron star or a black hole.   So that left the team with just one  conclusion: The main lens had to be   a white dwarf, a dense, cool star that is  the ultimate fate of stars like our Sun.   Along with this finding, there was one

unusual detail that drew researchers’ attention.   The shape of the lens had some abnormalities.

And they pointed to the presence of   a Jupiter-sized planet orbiting it

at a distance a few times larger than  . Earth’s orbit around the Sun. Which leaves one big question:   How in the world did that planet survive?

The process of going from an ordinary star like   the Sun to a white dwarf is a violent one. At the end of its life, a Sun-like star   puffs up to 100 times its original size. Then, it throws off its outer layers of gas,   which flow outward like a cosmic mop,

sweeping aside anything in their path,   and leaving behind a hot, dense core.

The researchers don’t speculate   as to how this planet survived. But it had to have been a wild ride.   In other surprising news, an article  published last month in the journal  . Physical Review D suggests  that experiments designed to   detect dark matter might actually be  capable of detecting dark energy, too.   This is stranger than it sounds,  because, despite their similar names,   dark matter and dark energy  are basically opposites.   Dark matter is the unseen  source of gravity that seems to   hold together the galaxies,  while dark energy is the   unknown force that is pushing the universe apart.

But, because dark matter and dark energy remain   basically unknown,

there are a bunch   of competing hypotheses to explain each. And some of them center on hypothetical particles   that happen to have similar properties. This paper in particular is trying to   explain some unexplained detections made

by a dark matter detection experiment   that ran in Italy between 2016 and 2018.

The observations it made aren’t easily   explained by any of the existing

dark matter hypotheses, so the researchers   went looking for another explanation. And they came up with a hypothesis based on   so-called chameleon particles. Unlike ordinary particles,   hypothetical chameleon particles

have different properties in different places.   In the past, theorists have  invoked them as a way to   explain what dark energy’s  physical form might be like.   The hypothesis is that, around other  matter, chameleon particles have   a lot of mass, but interact  with other matter very weakly.   Then when they’re on their own,  their mass drops to almost nothing,   while their interactions grow much stronger.

If that sounds super weird, it is,   but that’s kind of the point. Dark energy seems totally unlike   anything else in the cosmos. The research team simulated the   effects that a stream of chameleon particles

emanating from the Sun would have on the  .

Italian dark matter experiment,

and found a surprisingly close   match to what was actually observed. Now, that’s hardly a definitive statement, and,   in fact, the statistical significance of it

is far less than what is generally accepted in   particle physics. But it is an   eye-opening idea, and one that may cause

future detection experiments to consider a   wider range of possible targets.

After all, if you’re designing an   experiment to look for something that’s almost

totally unknown, you might as well cast a wide net   and see what else you can find! Thanks for watching this episode   of SciShow Space! If you want to support   the channel and get some great perks,

you can check out Patreon.com/SciShowSpace,   where we’ve recently added the  SciShow Space pin as a perk.   Sign up for our new Pin of the Month  Tier and each month you’ll receive   our featured pin of the month,  plus access to our newsletter,   questions inbox and Discord server. [♪ OUTRO]