The search for Planet Nine | Masao Sako | TEDxPenn
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0:17 - 0:18Hello, everyone.
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0:18 - 0:21It's late in the day,
so I'm going to start with a test. -
0:21 - 0:23(Laughter)
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0:23 - 0:26How many planets do we have
in our solar system? -
0:27 - 0:28Can't hear you.
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0:28 - 0:29(Audience) Eight.
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0:29 - 0:32Eight. Wasn't it nine?
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0:33 - 0:34What was the ninth one?
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0:34 - 0:36What happened?
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0:36 - 0:37Pluto, yes.
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0:37 - 0:40So I'm going to talk about
some of the research that I'm doing, -
0:41 - 0:44in particular, some new evidence
that's going to tell us -
0:44 - 0:48that there actually might be
the ninth planet in our solar system, -
0:48 - 0:49which is not Pluto.
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0:49 - 0:51So I'll describe how that goes.
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0:51 - 0:54You can see the planets behind me.
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0:54 - 0:57There are eight of them as you see
and you answer the question correctly. -
0:58 - 0:59Very good.
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0:59 - 1:04The first six which includes our Earth
have been known for a very long time. -
1:04 - 1:08Humans have been around
for maybe about a million years. -
1:08 - 1:10They probably saw it up in the sky.
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1:10 - 1:12They are visible with the naked eye.
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1:13 - 1:17The seventh and the eighth planet
are not so simple. -
1:17 - 1:21Uranus, for example,
can be barely seen with the naked eye. -
1:21 - 1:23If you go into a very dark place
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1:23 - 1:25and you stare at the sky
for a very long time, -
1:25 - 1:28you might be able to spot it.
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1:28 - 1:31Neptune is totally invisible to your eye.
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1:32 - 1:35Let me start with a little bit
of the history of what we know -
1:35 - 1:36about our solar system.
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1:37 - 1:40Like I said, the first six
have been known for a long time. -
1:40 - 1:42The seventh one, Uranus,
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1:42 - 1:47this one was the first planet
to be discovered using a telescope. -
1:48 - 1:52The telescope that was maybe this big,
fits on the size of your desk. -
1:53 - 1:55We now know that it orbits around the Sun
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1:55 - 1:58at an average distance
of about 19 astronomical units. -
1:58 - 2:01One astronomical unit
is the average distance -
2:01 - 2:03between the Sun and the Earth.
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2:05 - 2:08The eighth one, Neptune,
this has a very interesting story. -
2:09 - 2:12This planet was actually
predicted to exist -
2:13 - 2:15before it was discovered.
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2:15 - 2:17After Uranus' discovery,
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2:17 - 2:22physicists, astronomers were putting
Newton's law of gravity to the test. -
2:22 - 2:24They tried to make predictions -
-
2:24 - 2:29very precise predictions
of where Uranus would be on the sky, -
2:29 - 2:32and they tried to compare that
with the actual observations. -
2:32 - 2:35And they found
that it did not exactly match -
2:35 - 2:37where Uranus was supposed to be
-
2:37 - 2:39according to Newtonian gravity.
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2:39 - 2:42Half the people said:
''Oh, Isaac Newton is wrong," -
2:42 - 2:45half the people said:
"Maybe there's something out there.'' -
2:46 - 2:47It took some time,
-
2:47 - 2:52but it was actually finally predicted,
through lots of hard work, -
2:52 - 2:56that one night Neptune will appear
in this part of the sky, -
2:56 - 3:00and so astronomers should go
and look at that spot. -
3:00 - 3:02And lo and behold, within one degree,
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3:02 - 3:08which is about the size of your fingertip
at the distance of your arm, -
3:08 - 3:10it was found within 1 degree.
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3:10 - 3:16Now, Neptune is what we consider
the outermost planet in our solar system. -
3:16 - 3:18It orbits around the Sun,
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3:18 - 3:21at an average distance
of about 30 astronomical units. -
3:22 - 3:25Now, I have to say something about Pluto,
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3:25 - 3:27since Pluto was once a planet.
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3:28 - 3:30When I was in elementary school,
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3:30 - 3:33I did learn that Pluto
was in fact the ninth planet. -
3:33 - 3:38But in 2006, it was demoted down
to what we now know: a dwarf planet. -
3:38 - 3:42It's not quite a planet,
but maybe close enough. -
3:42 - 3:45Now, the person who demoted Pluto,
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3:45 - 3:48his name is Mike Brown,
a professor at Caltech, -
3:49 - 3:53he is not very popular
for obvious reasons, -
3:53 - 3:58but he and his colleague at Caltech,
Konstantin Batygin, -
3:58 - 4:03predicted that there might actually be
a true giant ninth planet -
4:03 - 4:06in the outskirts of our solar system.
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4:08 - 4:12Now, how do you look for things
in our solar system? -
4:12 - 4:16Well, if you look at the sky
and if you take a telescope -
4:16 - 4:19and measure, say, a portion of the sky,
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4:19 - 4:23a solar system object
looks just like a star; it's a dot. -
4:24 - 4:27The way to distinguish
a solar system object from a star -
4:27 - 4:29is through its motion.
-
4:29 - 4:32The Earth goes around the Sun once a year.
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4:33 - 4:36The object is also moving around the Sun.
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4:37 - 4:41So as the Earth goes
around the Sun once a year, -
4:41 - 4:46a solar system object
would appear to wobble in the sky. -
4:46 - 4:53So if you look at the actual motion
of, say, Pluto over a 10-year period, -
4:53 - 4:57it looks like this - that yellow coil
that you see in the back. -
4:57 - 5:01It takes exactly a year
to complete one loop. -
5:01 - 5:03It loops every year.
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5:03 - 5:06But at the same time, Pluto
is moving around the Sun, -
5:06 - 5:10and so you have a combined motion
of a circular motion -
5:10 - 5:12and a drift in one direction.
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5:13 - 5:16This is how you look
for solar system objects. -
5:17 - 5:24Now, let me tell you how Mike Brown
and his colleague at Caltech predicted -
5:24 - 5:27that there might actually be
a ninth planet in our solar system. -
5:27 - 5:31So these are the terrestrial planets,
which includes our own Earth. -
5:33 - 5:36Zoom out - those are our gas giants:
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5:36 - 5:39Jupiter, Saturn, Uranus and Neptune.
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5:40 - 5:44Now, if you'd zoom out even more,
there are a bunch of objects -
5:44 - 5:46but there are six in particular
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5:46 - 5:51that go way out to the outskirts
of the solar system, -
5:52 - 5:56to about maybe 400-500 times
the astronomical unit. -
5:57 - 5:58Now, you look at this, and say,
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5:58 - 6:01"Whoa, okay, there
are six of these things.'' -
6:01 - 6:02Do you see a pattern?
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6:03 - 6:05They're all pointed in this direction.
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6:06 - 6:10Now, if these were just random objects
orbiting around the Sun, -
6:10 - 6:15you would expect these elliptical orbits
to point in random directions. -
6:16 - 6:18The random chance of this occurring,
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6:18 - 6:21the fact that six are pointed
in the same direction, -
6:21 - 6:23and if you actually tilt this figure,
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6:23 - 6:27they are actually orbiting
close to a similar plane. -
6:27 - 6:30And so Mike Brown
and Konstantin Batygin said, -
6:30 - 6:33"Well, this is weird.
You can't explain this. -
6:34 - 6:36There's got to be something out there
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6:36 - 6:41that is possibly shepherding the orbits
into a particular direction." -
6:42 - 6:44And after a lot of hard work,
they came to the conclusion -
6:44 - 6:49that, yes, you can actually do this
if there's, in fact, a giant planet -
6:49 - 6:51they called Planet Nine
-
6:51 - 6:55with an orbit that is anti-aligned
with the really extended orbits. -
6:56 - 6:58So this is what we're trying
to do at Penn. -
6:59 - 7:02Penn is part of a large
international collaboration, -
7:02 - 7:05it's called the Dark Energy Survey.
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7:05 - 7:09We built this camera
and mount it on a telescope down in Chile. -
7:09 - 7:12You see the big shiny dome behind me,
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7:12 - 7:15that is the Blanco telescope,
a four-meter telescope down in Chile - -
7:15 - 7:18we built a camera
that's literally this big, -
7:18 - 7:20as tall as me, weighs about a ton,
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7:20 - 7:23and mount it
on the top end of the telescope. -
7:23 - 7:26What's special about this camera
is that it's huge. -
7:26 - 7:31In one shot, you can take
a very nice, crisp, deep picture -
7:31 - 7:33of a big part of the sky,
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7:33 - 7:37which is not something
that every telescope can do. -
7:37 - 7:41Now, this camera was built
for actually a different reason. -
7:41 - 7:44As the name suggests,
it's called the Dark Energy Survey. -
7:44 - 7:48We built this camera to try to study
the evolution of the universe. -
7:49 - 7:50How did the universe begin?
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7:50 - 7:52How is it expanding?
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7:52 - 7:54What is the ultimate fate of the universe?
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7:54 - 7:58That's what the other 200 astronomers
in our collaboration are doing. -
7:58 - 8:02But me and my colleague here,
Professor Gary Bernstein, -
8:02 - 8:03saw this and said,
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8:03 - 8:07"Well, this is a very good camera
which takes very good data. -
8:07 - 8:12You can actually use the same data
to find objects in our solar system." -
8:13 - 8:18This is a picture - one exposure
taken on our camera. -
8:18 - 8:21You can see the size
of the old camera in comparison, -
8:22 - 8:23which can fit the full moon.
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8:23 - 8:26We can fit many full moons in one shot.
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8:26 - 8:29It's half a billion pixels,
costs about 80 million dollars. -
8:29 - 8:32It's a very expensive instrument.
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8:32 - 8:35We're taking pictures every night,
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8:35 - 8:38and we're taking many,
many pictures every night, -
8:38 - 8:41and trying to look for things
that move across the sky. -
8:41 - 8:44Now, most of the objects
are stars and galaxies. -
8:44 - 8:47Stars move a little bit;
galaxies don't move at all; -
8:47 - 8:50solar system objects move quite a bit.
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8:51 - 8:56I'm showing you here about 0.05 percent
of the data that we have. -
8:57 - 9:01Each star that appear and disappear
are actual new things -
9:01 - 9:07that we discovered in this particular part
of the sky that were not present before. -
9:07 - 9:08There's a lot of them.
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9:08 - 9:10If you'd combine all
of the data that we have, -
9:10 - 9:13we'd have tens of millions
of new detections. -
9:13 - 9:17Most of them are asteroids,
main belt asteroids, -
9:17 - 9:22that orbit around the Sun,
between Mars and Jupiter, -
9:22 - 9:25but a small, tiny fraction of these
are things in our solar system -
9:25 - 9:27that are way out there.
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9:28 - 9:30So we take these detections,
millions of detections, -
9:30 - 9:34and try to connect the dots,
because like I said earlier, -
9:34 - 9:36solar system objects move.
-
9:36 - 9:40They move in a very particular way
according to Newtonian gravity. -
9:40 - 9:44So we take these detections,
take many, many computers, -
9:44 - 9:48and try to find
the few objects that match up, -
9:48 - 9:52that correspond to the same object
in the outskirts of our solar system. -
9:55 - 9:58So what happens is something
that looks like this. -
9:58 - 10:01I'm not showing you
all of the detections here. -
10:01 - 10:02I'm only showing you the detections
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10:02 - 10:07that correspond to actual solar
system objects that are way out there -
10:07 - 10:09beyond the orbit of Pluto.
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10:09 - 10:12In this small area, you can see
three camera pointings over here, -
10:12 - 10:16which adds up to
about 0.15 percent of our data, -
10:16 - 10:18we found 15 objects.
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10:18 - 10:23Now, try doing that with
a bunch of undergraduate students here. -
10:23 - 10:27Students here are absolutely great,
but if I tell them to do this manually, -
10:27 - 10:31connect a million dots and try to find
the ones that match up, -
10:31 - 10:33you really need a computer.
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10:33 - 10:35Now, I have to confess
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10:35 - 10:38that despite all the hard work
that we have done so far, -
10:38 - 10:41we have not yet found Planet Nine.
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10:42 - 10:45I probably wouldn't be here
if I had discovered it, -
10:45 - 10:46(Laughter)
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10:46 - 10:51but we did find at least
one interesting object that is rare. -
10:51 - 10:56And you look at this picture.
It's insignificant; it's that little dot - -
10:56 - 10:58of course it doesn't come with the arrow -
-
10:58 - 11:00it's that little dot that we discovered.
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11:00 - 11:02It looks like nothing,
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11:02 - 11:05but this turns out to be a distant
dwarf planet that we discovered. -
11:05 - 11:07It's just like Pluto.
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11:07 - 11:08It's way out there.
-
11:08 - 11:12It's slightly smaller than Pluto,
but this is the technology that we have - -
11:12 - 11:16we can see these things
out to very large distances. -
11:16 - 11:19Now, we've done
a lot of follow-up work on this -
11:19 - 11:21and try to identify its nature.
-
11:21 - 11:25We now know that it has an orbit
that looks like that -
11:25 - 11:28in comparison to the orbit of Neptune.
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11:28 - 11:31And you can see how the dots
move across three different nights. -
11:31 - 11:37Again, it's insignificant,
but computers are able to detect this. -
11:37 - 11:41Now this name DeeDee
comes from distant dwarf. -
11:41 - 11:45It's an acronym for distant dwarf,
and we put in the vowels in between. -
11:46 - 11:50We now know that it has a size
of about 600 kilometers - -
11:50 - 11:52it's a little bigger than Pennsylvania.
-
11:52 - 11:56But this thing currently
sits at 92 astronomical units. -
11:56 - 11:59You have this ball of rock
-
11:59 - 12:02that is roughly as big as Pennsylvania,
-
12:02 - 12:0792 astronomical units,
and we are capable of detecting it. -
12:07 - 12:10In terms of its brightness,
its current brightness, -
12:10 - 12:13it's comparable to taking a candlestick
-
12:13 - 12:16and putting it
at the distance of the moon, -
12:16 - 12:18and we are able to detect that.
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12:19 - 12:23Now, like I said,
we haven't found Planet Nine yet. -
12:23 - 12:26We have looked at about half of our data.
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12:26 - 12:31We're actively sifting through the rest
of the data that we have now. -
12:31 - 12:33Does it exist?
-
12:33 - 12:35I don't know.
-
12:35 - 12:38But if it's in our images,
we'll definitely find it. -
12:39 - 12:41And like Stephen Hawking said
-
12:41 - 12:45that we should all look up at the sky
and not down to your feet, -
12:45 - 12:46I'm trying to do that.
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12:46 - 12:48I'm trying to look up at the stars
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12:48 - 12:51with the hope of maybe
sometime in the future -
12:51 - 12:54finding this and understanding
more about our solar system. -
12:54 - 12:56Thanks for your time.
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12:56 - 12:58(Applause)
- Title:
- The search for Planet Nine | Masao Sako | TEDxPenn
- Description:
-
Dr. Sako is currently hunting for the putative giant planet - Planet Nine - that might be lurking in the outskirts of our Solar System. Planet Nine, if real, could be as large as ten Earth masses, but will only appear as a faint little dot due to its vast distance from the Sun. Dr. Sako and students use supercomputers to sift through the many millions of detections and background stars, galaxy, and other minor bodies in the solar neighborhood. Its discovery and nature will teach us about the history and formation of our Solar System. Masao Sako is an astrophysicist using large telescopes, supercomputers, and big data to study the Universe. He is the recipient of numerous teaching awards at the University of Pennsylvania, including the Lindback Award for Distinguished Teaching and the Dean’s Award for Innovation in Teaching.
This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at https://www.ted.com/tedx
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDxTalks
- Duration:
- 12:59
Rhonda Jacobs approved English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
Rhonda Jacobs edited English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
Rhonda Jacobs edited English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
Rhonda Jacobs edited English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
Rhonda Jacobs edited English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
Rhonda Jacobs edited English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
Rhonda Jacobs edited English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn | ||
hila scherba accepted English subtitles for The search for Planet Nine | Masao Sako | TEDxPenn |