ABOUT THE SPEAKER
Karen J. Meech - Astronomer, astrobiologist
Karen J. Meech is an astronomer who investigates how habitable worlds form and explores the bigger picture of whether there is life elsewhere.

Why you should listen

Astrobiologist Karen J. Meech uses the leftover pieces from our solar system's formation to understand how habitable planets are made. Her curiosity about life beyond earth was inspired as a child watching Star Trek. From this, her path led to a career in physics and astronomy, with a PhD in planetary physics from MIT. She is now an astronomer at the University of Hawaii, where she leads the astrobiology group, and she is a passionate scientific educator.

Meech started her astronomical career investigating comets, the icy leftovers from the birth of our solar system. Her work led to an understanding of many of the processes that cause the beautiful tails to develop far from our Sun. She was co-investigator on three comet missions. Her discoveries provide information to test our understanding of how planetary systems are assembled. Now her work has embraced the power of interdisciplinary science, and she is combining geological field work, geochemistry, astronomical observations, theory and space mission concepts to address fundamental questions about how earth got its water.

More profile about the speaker
Karen J. Meech | Speaker | TED.com
TED2018

Karen J. Meech: The story of 'Oumuamua, the first visitor from another star system

Filmed:
6,071,992 views

In October 2017, astrobiologist Karen J. Meech got the call every astronomer waits for: NASA had spotted the very first visitor from another star system. The interstellar comet -- a half-mile-long object eventually named `Oumuamua, from the Hawaiian for "scout" or "messenger" -- raised intriguing questions: Was it a chunk of rocky debris from a new star system, shredded material from a supernova explosion, evidence of alien technology or something else altogether? In this riveting talk, Meech tells the story of how her team raced against the clock to find answers about this unexpected gift from afar.
- Astronomer, astrobiologist
Karen J. Meech is an astronomer who investigates how habitable worlds form and explores the bigger picture of whether there is life elsewhere. Full bio

Double-click the English transcript below to play the video.

00:13
NASA's always on the lookout
for possible asteroid collision hazards,
0
1142
5454
00:18
so the Pan-STARRS telescope
is scanning the sky every night.
1
6620
4080
00:23
Each morning, candidate objects
are examined by Pan-STARRS staff
2
11231
4120
00:27
and usually discovered to be no big deal.
3
15375
3227
00:30
But on October 19, 2017,
4
18626
2739
00:33
Pan-STARRS spotted an object
moving rapidly between the stars,
5
21389
4652
00:38
and this time the usual follow-up
measurements of position and speed
6
26065
4318
00:42
showed something completely different.
7
30407
2815
00:45
By October 22nd, we had enough data
8
33246
2505
00:47
to realize that this object
wasn't from our solar system.
9
35775
4170
00:51
Holy cow.
10
39969
1341
00:53
That's when I got the phone call,
11
41334
1747
00:55
the phone call that all solar system
astronomers are waiting for.
12
43105
4006
00:59
Let me tell you how exciting this was.
13
47135
2111
01:01
(Laughter)
14
49270
1007
01:02
NASA's been expecting to see
an interstellar comet
15
50301
3121
01:05
pass through the solar system
since the 1970s,
16
53446
3340
01:08
but until now, we'd never seen anything.
17
56810
2858
01:11
Our own solar system is huge,
18
59692
2626
01:14
so even getting a package
from the nearest star system
19
62342
3309
01:17
4.4 light years away
20
65675
2103
01:19
would take over 50,000 years.
21
67802
2582
01:22
So this is a really big deal.
22
70408
2045
01:24
The interstellar visitor
entered our solar system
23
72945
2502
01:27
from above the plane of the planets,
24
75471
1850
01:29
coming from the direction
of the constellation Lyra,
25
77345
2833
01:32
and it passed closest to the Sun
on September 9th,
26
80202
3436
01:35
passing inside the orbit of Mercury.
27
83662
2405
01:38
Now this isn't a particularly
close approach or unusual distance.
28
86709
4029
01:42
It's just much easier
to see objects close by.
29
90762
3709
01:47
On October 14th,
30
95124
1676
01:48
before we discovered it, it made
its closest approach to the Earth,
31
96824
4102
01:52
within about 15 million miles.
32
100950
2690
01:55
This is really close
by astronomical standards.
33
103664
2757
01:59
Now rather than call this
by its unwieldy catalog name,
34
107341
4476
02:03
we briefly called it "Rama,"
35
111841
2643
02:06
after the cylindrical spacecraft
that passed through the solar system
36
114508
3508
02:10
in Arthur C. Clarke's classic
science fiction story in 1973.
37
118040
5214
02:15
But this wasn't quite right either,
38
123865
2077
02:17
so in honor of it being discovered
by a telescope in Hawaii,
39
125966
3233
02:21
we consulted two experts
on Hawaiian culture --
40
129223
3397
02:24
a Hawaiian navigator and a linguist --
41
132644
2453
02:27
to propose a name.
42
135121
1742
02:28
And they suggested "'Oumuamua,"
43
136887
2984
02:31
which means scout or messenger
from the distant past reaching out to us.
44
139895
5055
02:37
Now this discovery
was important for many reasons,
45
145972
3366
02:41
but to me the most significant
is for what 'Oumuamua can tell us
46
149362
3836
02:45
about the past of our solar system.
47
153222
2417
02:48
The process of the birth of a new solar
system and the growth of planets
48
156369
4041
02:52
can be a violent and messy business.
49
160434
3082
02:55
Leftover icy and rocky debris
gets ejected from the new solar system
50
163540
4223
02:59
as the giant planets migrate
through the dusty disk
51
167787
3349
03:03
out of which they're formed.
52
171160
1928
03:06
Now have you ever felt an emotional chill,
53
174175
3980
03:10
something that's so exciting
that a shiver runs up and down your spine?
54
178179
4801
03:16
Or something that's
very emotionally moving?
55
184115
2936
03:19
Well this was it for me.
56
187678
1747
03:21
This was my wow moment.
57
189449
1825
03:23
We actually had a piece of material
from another solar system
58
191298
3888
03:27
coming close enough for us to observe.
59
195210
3659
03:31
So what would you like to know
about 'Oumuamua,
60
199793
2858
03:34
the very first visitor
from another star system?
61
202675
3031
03:38
Well, I could think of a million things,
62
206454
2788
03:41
but there's what you want
and what you can have,
63
209266
3580
03:44
and 'Oumuamua was moving away
and fading very rapidly.
64
212870
4334
03:49
In the span of about a week,
65
217228
2201
03:51
it had dropped in brightness
by a factor of [10].
66
219453
2671
03:54
So this is about all the time
we were going to have
67
222852
2416
03:57
to study it easily.
68
225292
1887
03:59
So we had to distill the process
of getting telescope time --
69
227690
4922
04:04
normally a very competitive,
peer-reviewed proposal process
70
232636
3540
04:08
that can take up to months --
71
236200
1848
04:10
down to less than a few days.
72
238072
2699
04:12
So began a "polite"
competition for resources.
73
240795
3745
04:17
OK, let me not mince words.
It was a fierce battle.
74
245408
2794
04:20
We dropped everything,
75
248226
1768
04:22
working around the clock,
76
250018
1446
04:23
trying to craft
perfectly crafted proposal words
77
251488
3881
04:27
to send to the observatory directors.
78
255393
2245
04:30
Well, good news. We got the time.
79
258527
2848
04:34
Now, from a perfectly
selfish point of view,
80
262178
3563
04:37
the first thing we might like to know
is how massive 'Oumuamua is.
81
265765
4366
04:42
Because after all,
it passed very close to the Earth,
82
270155
2840
04:45
and we didn't know about it
until afterwards.
83
273019
3015
04:48
How bad would this have been
had it not missed the Earth?
84
276757
4301
04:53
Well, the impact energy
85
281950
1802
04:55
depends on the square
of the velocity times its mass,
86
283776
3609
04:59
and the mass depends
on how big it is and what it's made of.
87
287409
3596
05:03
So how big is 'Oumuamua,
and what's its shape?
88
291647
3421
05:07
Well, we can get this from its brightness.
89
295765
2320
05:10
Now, if you don't believe me,
think of comparing the brightness
90
298109
2967
05:13
of a firefly in your backyard
91
301100
1382
05:14
to the navigation lights
on a distant airplane.
92
302506
4420
05:18
You know the airplane is much brighter --
93
306950
1972
05:20
it just appears faint
because it's so far away.
94
308946
2700
05:24
We're also going to need to know
95
312775
1834
05:26
how reflective
the surface of 'Oumuamua is,
96
314633
3150
05:29
and we don't have any clue,
97
317807
2110
05:31
but it's reasonable to assume
it's very similar to small asteroids
98
319941
3860
05:35
and comets in our solar system,
99
323825
1982
05:37
or in technical terms,
100
325831
1350
05:39
something between the reflectivity
of charcoal and wet sand.
101
327205
4213
05:44
Nowadays, most of the big telescopes
are used in what's called a service mode,
102
332381
5715
05:50
meaning we have to carefully develop
all the instructions
103
338120
3856
05:54
and send them to the telescope operator,
104
342000
2549
05:56
and then anxiously wait
for the data to come back,
105
344573
2929
05:59
praying to the weather gods.
106
347526
2223
06:01
Now I bet most of you don't have careers
107
349773
2301
06:04
that critically depend on whether or not
it's cloudy last night.
108
352098
4811
06:08
Well, we weren't going to get
any second chances here.
109
356933
3167
06:12
Because the weather was great,
'Oumuamua decided not to be.
110
360124
4108
06:16
Its brightness wasn't constant.
111
364256
2000
06:18
Now here we see 'Oumuamua
racing between the stars.
112
366732
3215
06:21
It's centered in the middle.
113
369971
1579
06:23
The stars are trailed out because
the telescope is following its motion.
114
371574
3920
06:28
It started faint and then it got brighter,
fainter, brighter, and fainter again,
115
376145
5452
06:33
as sunlight is reflected off
of four sides of an oblong object.
116
381621
4825
06:39
The extreme brightness change
117
387302
2430
06:41
led us to an unbelievable
conclusion about its shape.
118
389756
4305
06:46
As shown in this artist's impression,
119
394085
1993
06:48
'Oumuamua is apparently
very long and narrow,
120
396102
3531
06:51
with an axis ratio of about 10 to one.
121
399657
3103
06:55
Assuming it's dark,
this means it's about half a mile long.
122
403479
3913
06:59
Nothing else in our
solar system looks like this.
123
407987
3548
07:03
We only have a handful of objects
that even have an axis ratio
124
411559
3438
07:07
bigger than five to one.
125
415021
1714
07:09
So we don't know how this forms,
126
417286
1979
07:11
but it may be part of its birth process
in its home solar system.
127
419289
5198
07:17
'Oumuamua was varying in brightness
every 7.34 hours,
128
425549
5469
07:23
or so we thought.
129
431042
1746
07:24
As more data started
to come in from other teams,
130
432812
2342
07:27
they were reporting different numbers.
131
435178
2458
07:29
Why is it the more
we learn about something,
132
437660
1926
07:31
the harder it gets to interpret?
133
439606
1940
07:34
Well, it turns out that 'Oumuamua
is not rotating in a simple way.
134
442596
3389
07:38
It's wobbling like a top.
135
446009
2059
07:40
So while it is rotating
around its short axis,
136
448092
3086
07:43
it's also rolling around the long axis
137
451202
2850
07:46
and nodding up and down.
138
454076
2070
07:48
This very energetic, excited motion
139
456887
2826
07:51
is almost certainly the result
of it being violently tossed
140
459737
3460
07:55
out of its home solar system.
141
463221
1922
07:58
Now how we interpret the shape
from its brightness
142
466363
2791
08:01
depends very critically
on how it's spinning,
143
469178
2872
08:04
so now we have to rethink
what it may look like,
144
472074
2970
08:07
and as shown in this beautiful painting
by space artist Bill Hartmann,
145
475068
3445
08:10
we think that 'Oumuamua
may be more of a flattened oval.
146
478537
3959
08:15
So let's get back to the energetics.
147
483822
1962
08:17
What is it made of?
148
485808
1911
08:19
Well, ideally we would love
to have a piece of 'Oumuamua
149
487743
3224
08:22
into the laboratory,
so we could study it in detail.
150
490991
3198
08:26
But since even private industry
can't manage to launch
151
494213
3667
08:29
a spacecraft within a week
152
497904
1762
08:31
to something like this,
153
499690
1667
08:33
astronomers have to rely
on remote observations.
154
501381
3161
08:36
So astronomers will look at how the light
interacts with the surface.
155
504566
3945
08:40
Some colors may get absorbed,
giving it a chemical fingerprint,
156
508535
4166
08:44
whereas other colors may not.
157
512725
2247
08:46
On the other hand, some substances
may just reflect more blue
158
514996
4253
08:51
or red light efficiently.
159
519273
1818
08:53
In the case of 'Oumuamua,
it reflected more red light,
160
521659
3723
08:57
making it look very much like the organic
rich surface of the comet recently visited
161
525406
5023
09:02
by the Rosetta spacecraft.
162
530453
1786
09:04
But not everything that looks reddish
has the same composition.
163
532887
4731
09:09
In fact, minerals that have
tiny little bits of iron in the surface
164
537642
3476
09:13
can also look red,
165
541142
1937
09:15
as does the dark side
of Saturn's moon Iapetus,
166
543103
2850
09:17
shown in these images
from the Cassini spacecraft.
167
545977
2785
09:21
Nickel-iron meteorites,
in other words, metal,
168
549432
2191
09:23
can also look red.
169
551647
1729
09:26
So while we don't know
what's on the surface,
170
554032
2670
09:28
we know even less
about what's on the inside.
171
556726
3146
09:32
However, we do know
that it must at least be strong enough
172
560435
3088
09:35
to not fly apart as it rotates,
173
563547
2372
09:37
so it probably has a density
similar to that of rocky asteroids;
174
565943
3960
09:41
perhaps even denser, like metal.
175
569927
2492
09:45
Well, at the very least,
I want to show you
176
573305
2071
09:47
one of the beautiful
color images that we got
177
575400
2142
09:49
from one of the ground-based telescopes.
178
577566
2140
09:52
All right, I admit,
it's not all that spectacular.
179
580145
2999
09:55
(Laughter)
180
583168
1012
09:56
We just don't have the resolution.
181
584204
2959
09:59
Even Hubble Space Telescope
182
587187
1929
10:01
doesn't present a much better view.
183
589140
2049
10:04
But the importance of the Hubble data
was not because of the images,
184
592220
3413
10:07
but because it extended
our observations out
185
595657
2492
10:10
to two and a half months
from the discovery,
186
598173
2683
10:12
meaning we get more positions
along the orbit,
187
600880
2704
10:15
which will hopefully let us figure out
where 'Oumuamua came from.
188
603608
4476
10:21
So what exactly is 'Oumuamua?
189
609667
2753
10:25
We firmly believe it's likely to be
a leftover archaeological remnant
190
613150
5523
10:30
from the process of the birth
of another planetary system,
191
618697
3588
10:34
some celestial driftwood.
192
622309
1848
10:36
Some scientists think
that maybe 'Oumuamua formed
193
624593
3383
10:40
very close to a star
that was much denser than our own,
194
628000
3595
10:43
and the star's tidal forces
shredded planetary material
195
631619
3413
10:47
early in the solar system's history.
196
635056
1850
10:49
Still others suggest that maybe
this is something that formed
197
637565
3961
10:53
during the death throes of a star,
198
641550
2166
10:55
perhaps during a supernova explosion,
199
643740
2792
10:58
as planetary material got shredded.
200
646556
2612
11:02
Whatever it is, we believe
it's a natural object,
201
650345
3508
11:05
but we can't actually prove
that it's not something artificial.
202
653877
4261
11:10
The color, the strange shape,
the tumbling motion
203
658710
3357
11:14
could all have other explanations.
204
662091
2111
11:16
Now while we don't believe
this is alien technology,
205
664825
3620
11:20
why not do the obvious experiment
and search for a radio signal?
206
668469
4642
11:25
That's exactly what
the Breakthrough Listen project did,
207
673640
2940
11:28
but so far, 'Oumuamua
has remained completely quiet.
208
676604
3702
11:33
Now could we send
a spacecraft to 'Oumuamua
209
681091
2779
11:35
and answer this question once and for all?
210
683894
2344
11:38
Yes, we do actually have the technology,
211
686262
2251
11:40
but it would be a long
and expensive voyage,
212
688537
2389
11:42
and we would get there so far from the Sun
213
690950
2278
11:45
that the final approach trajectory
would be very difficult.
214
693252
3293
11:49
So I think 'Oumuamua probably
has many more things to teach us,
215
697790
5071
11:54
and in fact there might be
more surprises in store
216
702885
2413
11:57
as scientists such as myself
continue to work with the data.
217
705322
4055
12:02
More importantly,
I think this visitor from afar
218
710138
3531
12:05
has really brought home the point
that our solar system isn't isolated.
219
713693
4762
12:10
We're part of a much larger environment,
220
718852
2414
12:13
and in fact, we may even
be surrounded by interstellar visitors
221
721290
4864
12:18
and not even know it.
222
726178
2033
12:20
This unexpected gift
223
728235
2112
12:22
has perhaps raised more questions
than its provided answers,
224
730371
4587
12:26
but we were the first to say hello
to a visitor from another solar system.
225
734982
5325
12:32
Thank you.
226
740712
1182
12:33
(Applause)
227
741918
6984
12:42
Jedidah Isler: Thanks, Karen.
228
750946
1455
12:44
I of course enjoyed
that talk very much. Thank you.
229
752425
2382
12:46
As I recall, we found it
pretty late in its journey towards us.
230
754831
3553
12:50
Will future technologies like
the Large Synoptic Survey Telescope
231
758408
3612
12:54
help us detect these things sooner?
232
762044
1713
12:56
Karen Meech: Yeah. We're hoping that
we'll start to see a lot of these things,
233
764353
3745
13:00
and ideally, you'd love to find one
as it's approaching the Sun,
234
768122
3819
13:03
because you want to have time
to do all the science,
235
771965
3016
13:07
or even more ideal,
236
775005
1197
13:08
you'd get a spacecraft ready to go,
237
776226
2065
13:10
parked somewhere in the L4 or L5 position,
238
778315
3150
13:13
somewhere near Earth,
239
781489
1334
13:14
so that when something comes by,
you can chase it.
240
782847
2991
13:17
JI: Awesome, thanks so much.
Let's thank Karen again.
241
785862
2549
13:20
(Applause)
242
788435
2664

▲Back to top

ABOUT THE SPEAKER
Karen J. Meech - Astronomer, astrobiologist
Karen J. Meech is an astronomer who investigates how habitable worlds form and explores the bigger picture of whether there is life elsewhere.

Why you should listen

Astrobiologist Karen J. Meech uses the leftover pieces from our solar system's formation to understand how habitable planets are made. Her curiosity about life beyond earth was inspired as a child watching Star Trek. From this, her path led to a career in physics and astronomy, with a PhD in planetary physics from MIT. She is now an astronomer at the University of Hawaii, where she leads the astrobiology group, and she is a passionate scientific educator.

Meech started her astronomical career investigating comets, the icy leftovers from the birth of our solar system. Her work led to an understanding of many of the processes that cause the beautiful tails to develop far from our Sun. She was co-investigator on three comet missions. Her discoveries provide information to test our understanding of how planetary systems are assembled. Now her work has embraced the power of interdisciplinary science, and she is combining geological field work, geochemistry, astronomical observations, theory and space mission concepts to address fundamental questions about how earth got its water.

More profile about the speaker
Karen J. Meech | Speaker | TED.com