How to find a planet you can’t see

Tiny wobbles and faint twinkles that have led astronomers to nearly 5,000 new worlds.

So when astronomers set out to search for planets around other stars (aka “exoplanets), they knew it wouldn’t be easy. Our closest neighbor, a little red dwarf named Proxima Centauri, is 7,000 times further away from us than Pluto. Any planets in orbit around it would likely get lost in the glare of bright starlight.

“Trying to see an earthlike planet across interstellar distances,” writes astrophysicist Adam Frank, “would be like looking from New York City to AT&T Park in San Francisco, where the Giants play, and making out a firefly next to one of the stadium spotlights.”

“To detect or study an exoplanet,” says Sara Seager, a planet-hunting astrophysicist at MIT, “we have to work with the star.”

Astronomers started monitoring stars for tiny changes that could hint at the presence of one or more planets. Early efforts focused on the search for a wobble. The pull of a planet’s gravity causes a star to circle their mutual center of gravity - and from our vantage point the star seems to swing back and forth. In 1995, a Swiss team picked up the signature of just such a wobble in the starlight from a yellow dwarf in the Pegasus constellation. They had found 51-Pegasi b: the first exoplanet around a sun-like star.

Fifty years ago, astronomers had no idea what percentage of stars had planets. A common educated guess was 20%, but for all we knew it could have been zero. But based on what we’ve seen since, it seems possible that every star has at least one planetary companion.

Now that we know exoplanets exist, it’s time to learn more about them. What are they made of? How did they form? And, most tantalizing, could they harbor life? We’re like sailors who have spotted a tiny rise of land on the horizon. Now we want to study this new island’s geology and biology and make contact with any inhabitants … but we have to do it all from aboard our ship, floating trillions of miles out at sea.

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Presented by the Center for Matter at Atomic Pressures (CMAP) at the University of Rochester,
a National Science Foundation (NSF) Physics Frontier Center, Award PHY-2020249

Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.
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Further reading:

The discovery of 51 Pegasi b:

The potential of the James Webb Space Telescope

The Smallest Lights in the Universe - Sara Seager’s memoir

Light of the Stars: Alien Worlds and the Fate of the Earth

The fraught and fractious history of failed exoplanet discoveries:

[emiliafilinto]

I love how you explain in a way that is not overwhelming that even a not so bright person like me can understand

[iSometimesWriteMusic]

This was expertly crafted educational material. Seriously, well done.

[TerryMun]

Even though appearing for just an insignificant amount of time in this video: that professor who dismissed Sara's ideas and then later kind of stake claim to it, is very, very real in academia and scientific research.

It's firstly gatekeeping: they say, oh, this is not possible.
And then when you make it, they say, oh, I've said that all the time: it's gonna be huge!

Thanks Vox for highlighting this: and props to Sara for soldering on despite people like that in her field. You go!

[Tomanna]

I'm so glad astronomy is coming into the eye of the public. Thank you for sharing, Vox!

[vasilerogojan]

Another proof that science is constantly advancing and we should use it in the most useful way as possible.

[Dr.SyedSaifAbbasNaqvi]

"We are universes way of experiencing itself" Space is the most beautiful and fascinating thing.

[varunnikam]

As a zoologist, I can say that people from the physics field think only earth type life can exist in this universe. But we only *know* earth-like life. The possibilities of life are endless. Understanding life is my favourite part of my life. Maybe life somewhere in this universe inhales H2SO4 vapours and exhale something different.
Thanks for the awesome video as always, Vox!

[aszamiilman]

I really adore how Vox involve Sara in this video. Not only i learned about astronomy but also learn her journey and the importance about the things that she working on.

[Sid_Kill]

It's fascinating how long we've come in our space exploration journey and technology but sadly we are not even half way there in knowing or discovering any mysteries of our universe.

[joycejames]

It's reassuring to know that there are people looking out there for the bigger picture while so many of us are bogged down in day to day life.

[spacefaringculture]

Great video, as always!

If anyone reading this comment is interested in how planetary scientists work, I highly suggest reading "Placing Outer Space" by anthropologist Lisa Messeri. It goes into detail about all of this (and much more) from a social perspective. I studied it while researching for my thesis and I thoroughly enjoyed it.

[sparshabanik]

Vox has been fascinating me for so long that now I’m finally getting the opportunity to major in astrophysics! (I’m studying these same concepts right now!)

[taytsay]

I know this entirely isn’t the point but that rainbow chalkboard shot was so cool!

[muhammadsaad-crbw]

Now thats what i call perfection 👌. I’m talking about the presentation. How well you transformed that un-understandable information to something everyone could understand.

[shaishabrai]

Wouldn't the wobble of the star caused due to cumulative effect of all the planets? How can that wobble be singled out for a particular one planet? Someone explain.

[etcetera]

Really well made Vox…..you make it look so easy

[virginia]

Enjoying Vox partnering with Sara for these videos, she is so informative and her passion really shines through!

[jeffsplur]

Vox, I appreciate your team and the work you guys do. It’s the only journalism on Youtube that I love.

[notamemethememe]

I saved this video to my watch later playlist, but I kept skipping over it because I thought it would be difficult for me to understand. I was pleasantly surprised that I watched the whole video, and even went to go back to it when YouTube glitched in between. The video was simple to understand, educational, and wasn't boring. Keep going, Vox. ❤

[syedjafferimam]

A video that actually teaches you how astronomy works. Excellently made video.