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Science, Technology and the Environment
Proxima B
– Potentially habitable, and Right on our Doorstep!
Just over 20 years ago, the only
planets we knew about were the ones
in our own solar system orbiting the
Sun. Since then, astronomers have
discovered thousands more planets in
orbit around distant stars.
Discovering a “wobble”
Many are gas-shrouded giants like
Jupiter. That’s not the kind of planet
where we would expect to find life as
we know it. To support life, a planet
would need to be more like our Earth.
“People seem to think we just found
the planet. But no, we have believed
it was there for years,” explained Dr.
Anglada-Escude. “We just had to build
an argument to convince others it
exists.”
A star is a huge ball of gas held
together by gravity. The central core
is extremely hot and produces energy.
Some of this energy is released as
visible light, which makes the star
glow.
He and his colleagues deduced the
existence of the planet from the
gravitational influence it has on the
star around which it orbits.
Stars are different colours and
temperatures. They range is size, too,
from dwarfs to supergiants. Our Sun,
the center of our solar system, is a
yellow star of average temperature and
size.
Turns out there is a suitable candidate
right on our doorstep.
Proxima b
On August 24, an international team
of scientists reported they had found
a potentially habitable planet orbiting
around Proxima Centauri, the closest
star beyond our solar system.
“For more than 20 years the history
of exoplanets has been defined by
studying the stars tens to hundreds
of light-years away, when the holy
grail – a small, rocky, potentially
habitable planet – was just waiting
to be discovered around our closest
neighbour,” says veteran astronomer
Debra Fischer from Yale University.
The discovery of Proxima b was
spearheaded by British astronomers
Guillem Anglada-Escude and Mikko
Tuomi. It was a long time coming, but
it was not out of the blue.
Orbiting worlds give their stars
a slight but distinctive “wobble.”
Using an ultra-precise instrument
mounted on a telescope in Chile,
Dr. Anglada-Escude’s team detected
this signal from Proxima Centauri.
The team then confirmed its findings
using other telescopes.
The Goldilocks zone
Proxima Centauri is a red dwarf,
which means it is a small star, and
only about one thousandth as bright
as our sun. Proxima b huddles close,
About Stars
and Planets
Stars are the building blocks of
galaxies. Our Milky Way galaxy alone
has about two hundred billion of them.
Planets are roughly spherical objects
that orbit stars. They are believed
to have been formed from the discshaped clouds of gas and dust left over
from a star’s formation. Astronomers
now estimate that fifteen to thirty
percent of the stars in our galaxy could
have planets orbiting them in the
Goldilocks zone.
Definitions
exoplanet: a planet that orbits a star outside the solar system
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Science, Technology and the Environment
Proxima B
– Potentially habitable, and Right on our Doorstep!
orbiting just 7.5 million kilometres
away and taking 11.2 days to complete
one orbit.
Despite being much closer to its
star than the Earth is to the Sun,
Proxima b has temperatures that are
not too hot. It resides in what scientists
call “the Goldilocks zone” – where
conditions are “just right” for any
water on its surface to be in liquid
form.
Furthermore, Proxima b’s mass is
about one-third more than the Earth’s.
This suggests that it is rocky, with a
solid surface on which seas and oceans
could pool. That also means that it
has Earth-like gravity; if people lived
there, they wouldn’t be crushed or
float away.
While that makes Proxima b
potentially habitable, humans would
not find living on the planet pleasant.
One side is constantly bathed in light,
the other is always dark, and it is
vulnerable to violent solar flares from
its star. But that doesn’t rule out the
presence of other biological organisms.
“The search for life on Proxima b
comes next,” says Dr. Anglada-Escude.
Zeroing in
Proxima b may be on our doorstep
in astronomical terms, but it is still
4.4 light years away. That’s about 40
trillion kilometres. So don’t expect
spaceships to be heading there for a
close-up anytime soon. Using current
technology, it would take about 75,000
years for a spacecraft to reach the
planet. So how can we find out more
about this planet? How can we get a
better look?
Breakthrough Starshot
What if you could send super-fast, miniscule spaceships propelled by
lasers to Proxima Centauri? Such devices would travel at about 20
percent the speed of light – about a million times faster than a car on the
highway – and slash the time needed for the trip to about 20 years.
That’s the idea behind a $100 million project called ‘Breakthrough Starshot’
that aims to build and send thousands of ‘nanocraft’ weighing a gram each
to Alpha Centauri, the triple-star system that includes Proxima Centauri.
The scientists working on this bold idea are backed by some big names:
cosmologist Stephen Hawking, Facebook founder Mark Zuckerburg and
tech billionaire Yuri Milner. They announced Breakthrough Starshot
just four months before the news of Proxima b’s discovery broke.
Is Starshot a crazy idea? Certainly it faces enormous technological challenges.
Tiny spacecraft travelling at 60,000 kilometres per second would be damaged
by any collision with gas or dust particles. Another difficulty will be sending
data from the spacecraft back to Earth. The biggest hurdle will likely be
building the super-powerful lasers that will propel the spacecraft.
Yet, says Mr. Hawking, these are solvable problems. “These are not
limitations set by the laws of physics. They are engineering problems.
Engineering challenges tend, eventually, to be solved.”
Stay tuned to see what happens next! Mr. Hawking’s been right before.
The greatest hope among planet
hunters is that Proxima b’s orbit takes
it across the face of Proxima Centauri
as viewed from Earth. It would then
cast a minuscule but measurable
shadow towards our waiting
instruments. This might confirm
the existence of an atmosphere, and
perhaps yield some information about
its chemical properties. A protective
atmosphere is a ‘must have’ for a
life-friendly planet.
If that doesn’t work, we might
someday be able to actually capture
a direct image of the planet using
the next generation of gargantuan
telescopes now under construction
around the world.
A game-changer
Experts say that the discovery of
Proxima b will re-shape astronomical
perspectives and priorities. The
exoplanet is a concrete target on which
scientists can focus their research,
instead of “throwing darts randomly
at the sky,” as one described it.
“I think it’s the most important
exoplanet discovery there will ever
be,” says Dr. Carole Haswell from
Britain’s Open University. “How can
you ever trump something that could
be habitable orbiting around the very
closest star to the Sun?” J
Definitions
atmosphere: the envelope of gases surrounding the Earth or another planet
laser: a device that emits a very narrow and intense beam of light or other radiation
solar flare: a brief powerful eruption of particles and intense electromagnetic radiation from a star’s surface
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Science, Technology and the Environment
Proxima B
– Potentially habitable, and Right on our Doorstep!
ON THE LINES
Answer the following in complete sentences:
1. Explain what a star is.
2. Explain what a planet is.
3. Explain what it means for a planet to be in the Goldilocks zone?
4. What is Proxima Centauri?
5. How far from Earth is this star?
6. What did scientists announce in late August regarding this star?
7. What do scientists know about this planet?
8. How did astronomers find this planet?
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Proxima B
– Potentially habitable, and Right on our Doorstep!
BET WEEN THE LINES
An inference is a conclusion drawn from evidence. A plausible inference is supported by evidence in the article and is
consistent with known facts outside of the article.
What inference(s) can you draw from the fact that a group of billionaires is willing to invest its own money in cosmic
discovery?
BEYOND THE LINES
Proxima b isn’t humanity’s only target for finding life beyond Earth. NASA recently announced that, in 2038, it will go
where it’s never gone before: underwater. The surface of Titan, one of the moons of Jupiter, has some of the largest bodies
of liquid ever seen. Learn more about this or other current/planned missions into outer space.
JUST TALK ABOUT IT
1. Consider: “What makes human beings unique? Some say it’s language or rules. Others say it is logical reasoning. They
obviously hadn’t met many humans. I believe what makes us unique is transcending our limits.” - Steven Hawking
a) What words are you unsure of the meaning of? Find definitions for them.
b) What is your understanding of this quote?
c) In what ways does this quote relate to the article? Explain.
d) Respond to this quote. For what reasons do you agree with the speaker? For what reasons do you disagree?
2. Exploring space is expensive. As you see it, is the chase for cosmic answers worth the investment? Explain.
ONLINE
Note: The links below are listed at www.lesplan.com/en/links for easy access.
1. Read about the six most Earth-like alien planets that we know about at
http://www.space.com/30172-six-most-earth-like-alien-planets.html
2. Watch a short, superb video about Proxima b at https://www.youtube.com/watch?v=BG1CwK0MIFQ
3. Watch an inspiring Breakthrough Starshot introduction called “Breakthrough Starshot Introduced by Seth McFarlane”
at https://www.youtube.com/watch?v=hgatMcul2zw
4. Watch a PBS feature on Breakthrough Starshot called “Will Starshot’s Insterstellar Journey Succeed?” at
https://www.youtube.com/watch?v=fsARBnvUB2E
5. Earn $1,000,000 by designing a message for aliens with Breakthrough Message. Explore more about Breakthrough
Starshot and Breakthrough Listen while you’re there: https://breakthroughinitiatives.org/ J
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– Potentially habitable, and Right on our Doorstep!
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ACROSS
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5. proposed propulsion source for tiny spaceships
1. spherical object that orbits a star
7. a tubular instrument that uses lenses to make
distant objects appear larger
2. a star’s central core is very hot and produces _____
8. Proxima b is 40 _____ kilometres from Earth
10. the gases that surround the Earth
3. a star is a huge ball of gas held together by _____
4. The _____ Zone
13. Breakthrough _____
6. orbiting planets give their stars a slight but
distinctive _____
14. solar _____
9. galaxy name (2)
15. the scientific study of stars, planets, and other
objects in space
11. a planet that orbits a star outside our solar system
16. Proxima _____ is the closest star to our solar system
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12. necessary for life and must be in liquid form
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