
First Ever Image of a Multi-Planet System Around a Sun-Like Star Captured by ESO - rbanffy
https://www.eso.org/public/news/eso2011/?lang
======
ChuckMcM
This is nice work. I am amazed at the advances in planet discovery from "other
stars 'might' have planets" to post Kepler "more than half the stars have
planets."

The other "unknown" is under what conditions can intelligent life evolve? Once
you know that window, the Drake equation gets even more interesting.

The notion that we are the only intelligent species in the galaxy seems more
and more unlikely.

~~~
kazagistar
The more unlikely it gets that we would be the only intelligent life, the more
dire our future outlook, due to the lack of signs of intelligent civilization
in the stars. If they must have existed, then there must also be a reason they
don't anymore.

~~~
credit_guy
> the lack of signs of intelligent civilization in the stars

And what would such sings look like? The only conceivable sign that we could
observe with our current technology is Dyson spheres. It's however entirely
reasonable that intelligent civilizations can advance to quite highly
technological levels and not develop Dyson spheres.

If a civilization like ours were to inhabit the nearest star system, Proxima
Centauri, and zip happily in rockets from one planet to another (of which
there are at least 2 confirmed), and beam radio messages back and forth among
themselves, would we be able to tell?

~~~
guerrilla
Not to mention that there may be alternatives to Dyson swarms that anyone
capable of building one learns about on the way to gaining that capability.

I'll start listening to people telling me about missing signs after we have a
unified theory of physics that includes an interpretation of QM, quantum
gravity with proper explanations for galactic rotation and inflation among
other things.

------
colanderman
Make sure to click the lead image to see the star also.

~~~
colanderman
Aha, apparently there is an image sidebar which is hidden on mobile, where is
given the following reason for the star's haloed appearance:

"The image was captured by blocking the light from the young, Sun-like star
(top-left of centre) using a coronagraph, which allows for the fainter planets
to be detected. The bright and dark rings we see on the star’s image are
optical artefacts."

------
Diederich
A recent video talking about what it could take to get high resolution imagery
of exoplanets. The video title is a bit hand wavy, but it basically involves
using the sun as a gravitational lens:

[https://www.youtube.com/watch?v=NQFqDKRAROI](https://www.youtube.com/watch?v=NQFqDKRAROI)

~~~
fadedasmygenes
This was great. Thanks for sharing!

------
dekhn
Telescopes like VLT, the LIGO experiment, CERN LHC and ATLAS, and a few others
really represent the state of the art in terms of precision as applied the
science.

I got fascinated with the challenges associated with building high precision
systems (which has been an ongoing pursuit since the beginning of the
industrial revolution that has led to untold scientific and economic wealth).
It's not easy. Progress depends on large numbers of people working together
across multiple fields to build systems that are often only a few percent
better than the previous generation. Sometimes, there are breakthroughs and
fields progress rapidly, only to end up stagnated as they reach their
theoretical limits or other bottlenecks.

What humans have achieved, over the course of civilization is really quite
extraordinary and we shouldn't ignore that what people were doing at the
beginning of civilization required precision as well, but the precision
depended far more on the physical skills of the artisan, than their ability to
use their brain and capital to make highly precise objects.

Two of the most powerful techniques that came from the mastery of precision
are interferometry (the process of collecting and combining multiple light
waves) and spectroscopy (the process of collecting frequency-resolved photon
distributions).

I'm building an alt-az mount for a raspberry pi solar scope at home; it weighs
a few pounds. Each of the scopes at ESO (there are 4, allowing them to exploit
interferometry to increase their angular resolution) is a building that is an
alt-az mount that weighs 350 _tons_.

~~~
867-5309
> few pounds

> 350 tons

what is the significance of this?

~~~
nitrogen
Shows the scale of the telescopes by comparing the massiveness of a homemade
vs. state-of-the-art whole-building altitude-azimuth mount. It's amazing that
something that ways 350 tons can be aimed with precision at photographic
targets that are constantly moving with the rotation of the earth.

~~~
867-5309
so what does this mean? how does being bigger and heavier affect the outcome?

~~~
dekhn
it's just impressive at scale.

------
VikingCoder
Someone want to do the math for me? How many arc-angles per pixel in this
image? And then, with those arc-angles, what sized object could you resolve
(as larger than one pixel) on the moon?

~~~
mturmon
> ESO ... has taken the first direct image of a planetary system around a star
> like our Sun, located about 300 light-years away...

> The two gas giants orbit their host star at distances of 160 and about 320
> times the Earth-Sun distance.

For our purposes, a parsec [pc] is 3 ly, so the host star is at 100 pc. The
inner planet is at 160 AU, which we'll round to 100 AU.

So the angular separation is 100 AU / 100 pc = 1 AU/pc = 1 arcsec, and their
resolution must exceed this.

And then we have this handy chart:

[https://astronomy.stackexchange.com/questions/20695/how-
big-...](https://astronomy.stackexchange.com/questions/20695/how-big-is-one-
arcsecond-at-various-distances)

This illustrates that the key issue is not resolution itself. It's contrast,
at this high resolution. Because the planet must be distinguished from the
host star.

I don't know what the contrast difference here is. For Earth-like exoplanets
(smaller targets at 1AU), the contrast difference is 10^10. That is, for every
10 billion photons from the host star, you get one reflected from the
exoplanet.

[edited to add: using the link provided by @teraflop, Table 1, column 3 seems
to show a contrast of about 10-12 in magnitude units, which is 10^4 to 10^5 in
physical units like photons]

~~~
raducu
300 AU?

Isn't that exeedingly far? Like 10 times farther away from Pluto?

Would we even be able to detect such a planet if it orbited the Sun?

~~~
vl
In the article they say that these planets are young and hot and they detected
them in infrared by blocking light from the host star using special device. We
would easily detect such super-massive hot planet at 300 AU in the solar
system, but there is no reason for them to exist here since solar system is
much older.

~~~
raducu
I was thinking that in out case hot or cold is not the main issue, but the
area where to look.

If you look at a star 300 light years away, you just have to search a couple
of pixels away from the star.

But if you searched for such a planet at 300 AU from out Sun, you would have a
massive amount of space to search throug -- like a massive cilindrical wall of
space around the Sun(if it was not exactly on our plane around the Sun).

But in anycase, I was wondering if we had such a planet in our solar system,
but obviously cold by now, could we detect it?

~~~
nitrogen
_(if it was not exactly on our plane around the Sun)_

On that matter, are there any significant objects (natural or artificial)
orbiting way outside the plane of the solar system?

~~~
iso947
Eris is inclined 44 degrees. I think the highest inclination artificial
satelite is Parker Solar Probe, about 3.4 degrees

~~~
mturmon
Your comment jogged my memory. Ulysses, a cleverly-named solar-polar mission,
used a deployment from the Shuttle, and a gravity assist from Jupiter, to
reach an inclination of 80 degrees.

From [https://www.cosmos.esa.int/web/ulysses/the-ulysses-
mission](https://www.cosmos.esa.int/web/ulysses/the-ulysses-mission):

> Because direct injection into a solar polar orbit from the Earth is not
> feasible, a gravity-assist is required to achieve a high-inclination orbit.
> As a result, Ulysses was launched at high speed towards Jupiter in October
> 1990, after being carried into low-Earth orbit by the space shuttle
> Discovery. Following the fly-by of Jupiter in February 1992 /3/, the
> spacecraft is now travelling in an elliptical, Sun-centred orbit inclined at
> 80.2 degrees to the solar equator.

------
sosuke
I can't continue down this rabbit hole so I'm asking for a handout. I remember
reading about the limitations of light and contrast to resolve smaller details
on the moon or other solar systems like this. I've since lost the details and
links to time.

Is there any upper limit, physically, to this? Would it be possible on paper
to design a system that could take pictures of the moon where you could see
individual strands of hair on a human?

I'm curious if we might at some point construct enormous arrays of telescopes
spanning large (human perspective) sections of space that could give us a
window into our galaxy.

~~~
throwaway2048
[https://en.wikipedia.org/wiki/Diffraction-
limited_system](https://en.wikipedia.org/wiki/Diffraction-limited_system)

There is a fundamental relationship between wavelength of light and focus-
ability/magnification.

You could in principle build an increasingly larger lense to get around the
problem, but eventually that hits practical limits.

~~~
webmaven
Can't you create ever larger arrays of reasonably sized lenses? And "array"
just means "two or more widely separated by a known distance", so opposite
sides of (polar?) orbit should work.

------
jackfoxy
The mass of the larger of the 2 planets seems to be on the verge of brown
dwarf classification
[https://en.wikipedia.org/wiki/Brown_dwarf](https://en.wikipedia.org/wiki/Brown_dwarf)

------
hanoz
Do both these planets just happen to be passing in front of the star then,
because they would typically be a mile or so outside the image at that scale
wouldn't they?

~~~
Roboprog
No, they are imaged in reflected light, rather than a transit (silhouette).

The parent star is masked off, and I’m pretty sure it’s an image generated
from multiple telescopes, “interferometry”, as others have mentioned.

~~~
SiempreViernes
No, this was actually shot with SPHERE, which is a single telescope
instrument: [https://www.eso.org/public/teles-instr/paranal-
observatory/v...](https://www.eso.org/public/teles-instr/paranal-
observatory/vlt/vlt-instr/sphere/)

~~~
Roboprog
Interesting. It’s attached to one of the VLTs

[https://en.wikipedia.org/wiki/Very_Large_Telescope](https://en.wikipedia.org/wiki/Very_Large_Telescope)

Unclear if they use the auxiliaries as part of the process.

------
nsxwolf
Why do they appear so large and so close together in the photo? (Assuming that
is an image of the star and one of the planets). Are they really point
sources, blooming to cover more pixels?

~~~
pavlov
Click on the image to reveal the entire image: there’s a star and two planets.

(It’s ridiculous that they would publish the image cropped like this.)

------
throw1234651234
Why a picture of this and not Alpha Centauri at ~4 ly?

~~~
peroporque
Alpha Centauri has a binary system with another third sun orbiting the other
two at half a light-year or so. Not very "sun-like".

~~~
throw1234651234
However, it has planets thought to be in the Goldi-locks zone around one of
the stars. Seems like if they can get that kind of resolution at 300ly, they
should be able to do infinitely better at 4. Just a thought, I am sure I am
missing something.

~~~
infogulch
A comment upthread mentions that one of the biggest obstacles to detecting
planets is the huge contrast between the planet and its host star: detecting
10-14 orders of magnitude difference between the luminosity of a star and
orbiting planet cannot be made simpler by adding in 2 additional stars.

------
etxm
I kind of love that the first system photographed(?) is in a different
orientation and that we have a “top” down view of it.

~~~
Johnjonjoan
I think the multi-planet system part is what makes it a first.

~~~
dylan604
How do you mean? That it it was photographed in such a manner? We definitely
know of plenty of several systems with multiple planets.

~~~
Johnjonjoan
Yes that's exactly how I understood it. Otherwise anyone who has taken a
picture of the night sky probably beat this image.

------
hoseja
So it's more like a triple star system of two brown dwarfs and one star?

------
davedx
Incredible. 300 light years away and photographed by a ground based telescope.
We keep pushing the boundaries. I’m excited for the next couple of decades of
astronomy. What more will we see?

~~~
Gys
Proof of life outside earth would be the coolest

~~~
arethuza
Some people think that would be _very bad_ as it would suggest that the Great
Filter is in our future rather than our past:

[https://en.wikipedia.org/wiki/Great_Filter](https://en.wikipedia.org/wiki/Great_Filter)

~~~
bosswipe
Maybe the Great Filter is global warming, or other similar planetary
pollution. Once a civilization ramps up Moloch[1], the self-reinforcing self-
perpetuating structures necessary to organize industry at a planetary scale,
it becomes too difficult to pull back and stop it before it's too late.

[1]
[https://www.lesswrong.com/posts/TxcRbCYHaeL59aY7E/meditation...](https://www.lesswrong.com/posts/TxcRbCYHaeL59aY7E/meditations-
on-moloch)

~~~
throwaway0a5e
Unlikely.

We're going to have a hard time dumping enough anything into the atmosphere
(or causing some other kind of pollution) to kill ourselves entirely. We'd
osculate around an equilibrium where we dump some pollutant into our
environment to the point where our population decreases, natural processes
remove it and our population increases, wash, rinse, repeat. You can see
similar population and resource usage patterns in many ecosystems.

And before anyone tries to twist my words to saying global warming isn't a bad
thing, that's not what I'm saying. I'm just saying that humans as a species
will likely survive it.

~~~
bosswipe
It's not species extinction that makes life undetectable, it's extinction of
the civilization. For a civilization to be detectable it has to be at least at
our level, or maybe a century beyond our level. If our civilization collapses
it would mean that we were only detectable for a couple of centuries and then
it could take millennia for us to get back to our level, especially if we've
extracted all the easy to extract natural resources making it harder for our
ancestors to rev back up, or if large parts of the planet become
uninhabitable.

~~~
throwaway0a5e
>it's extinction of the civilization. For a civilization to be detectable it
has to be at least at our level,

My point is that we won't go extinct, we'll bounce back and get another try.

>especially if we've extracted all the easy to extract natural resources
making

Would you rather hollow out a mountain to mine minerals or dredge through what
used to be a major city? We've concentrated all sorts of useful things on
earth's surface. If anything the next civilization will have it easy.

>harder for our ancestors to rev back up, or if large parts of the planet
become uninhabitable.

Large parts of the planet _were_ more or less uninhabitable. The few people
who lived in the arctic and the deserts mostly just followed food/water
sources. They contributed little to civilization's progress (mostly in the
field of astronomy because desert nights and polar winters give you plenty of
time to look at the starts) because they didn't have the spare resources to
engage in those pursuits because they were too busy surviving. Progress has
always come from the places that are easy to live in and therefore have
resource surpluses.

~~~
bosswipe
Separate from the details of the consequences of global warming itself, more
generally my hypothesis is that in order for a civilization to become aware
that it is consuming too many natural resources requires a level of advanced
development that can only be achieved by consuming too many resources. In
other words, it might be more likely than not that when a planet produces a
civilization that enters an industrial revolution it ends up burning through
its natural resources in an unsustainable way and ends up collapsing. The easy
access to resource surpluses that ignites the industrial revolution is also
what causes them to overshoot their planet's capacity.

For us it's not just CO2 pollution that is a problem, there are many other
resources that we are over-utilizing in an unsustainable way. And it seems
that we are completely incapable of coordinating as a planet when the
sacrifices are large. The hope of the techno-optimists is that technology will
save us. It's a high-stakes bet that technology will figure it out before it's
too late. Maybe the Great Filter is that when this bet is made across the
universe the odds are generally in favor of losing.

------
m3kw9
2 dots one white and one orange.

~~~
glouwbug
You could say the same about us - the blue dot

------
peroporque
Great. And now let's build a telescope on the dark side of the moon!

~~~
michael_j_ward
The dark side is only dark from our perspective on earth. It still receives
two weeks of sunlight a month.

If you wanted to minimize sunlight, you'd want to put a telescope at L2 [1],
which is in fact where the James Webb Space Telescope will be deployed [2].

It's launch was recently pushed back from March to October of 2021 [3] (or [4]
for non paywalled version)

[1] [https://www.space.com/30302-lagrange-
points.html](https://www.space.com/30302-lagrange-points.html)

[2]
[https://en.wikipedia.org/wiki/James_Webb_Space_Telescope](https://en.wikipedia.org/wiki/James_Webb_Space_Telescope)

[3] [https://www.nytimes.com/2020/07/16/science/nasa-james-
webb-s...](https://www.nytimes.com/2020/07/16/science/nasa-james-webb-space-
telescope-delay.html)

[4] [https://outline.com/bsWKnf](https://outline.com/bsWKnf)

~~~
dylan604
And at L2, we'll never be able to upgrade it or even service if something were
to go wrong before end of scheduled mission. Something on the moon would be
much more accessible for upgrades or basic servicing missions. Even with 2
week on/2 week off schedule, it would be so useful. During those 2 weeks off,
it would be charging its batteries. Never would it suffer from cloudy nights.

~~~
Rebelgecko
OTOH, a trip to the moon requires about 10x more fuel than going to L2.
Although I suppose a moon telescope could synergize nicely with other lunar
activities

Edit: I think I misread the table I was looking it, it's more like 2x or 3x
instead of 10x, and that assumes a start from LEO

