THE LEADING EDGE - Alien Life in Solar Systems

"Hunt for alien life zooms in on newly discovered solar system" PBS NewsHour 2/22/2017

An artist's impression of TRAPPIST-1
 and its seven planets

Excerpt

SUMMARY:  Astronomers have identified seven Earth-sized planets orbiting a star that's just a mere 230 trillion miles from our own planet, raising the tantalizing prospect of life in a solar system beyond our own.  Science correspondent Miles O'Brien joins Hari Sreenivasan to discuss how they made the discovery and what it means.

HARI SREENIVASAN (NewsHour):  Now to this week's edition of Leading Edge.

There is new excitement tonight about the search for possible life in a solar system beyond our own.  Astronomers have identified seven Earth-sized planets orbiting a star just a mere 230 trillion miles or so from our own planet.  That sounds like a mind-boggling distance.  It is.  But researchers say the idea of life on one of these exoplanets, as they're called, is tantalizing.

Astronomers, using ground and space telescopes operated by NASA and the European Southern Observatory, made the announcement.

Our own Miles O'Brien is here to guide us through the news.

First of all, if something is so far away — this is maybe a basic science question — how do we know what we know and what we saw?

MILES O'BRIEN (NewsHour):  It's a good question.

You know, think about it for a minute.  If it's trillions of miles away, how is it even possible?  So, imagine — the technique is called transit photometry.  Now, imagine you're about a mile away from a headlight and a mosquito goes across the headlight.

Believe it not, that headlight is slightly dimmed by the fact that mosquito goes across.  Well, this is tantamount to what they do.  The planet goes in front of the star, it dims ever so slightly, and with a lot of complicated and sensitive instrumentation, you can determine that, in fact, that's a planet.

They discovered three of them this way.  They said, hmm, this is an interesting, ultra-cool brown dwarf to look at.  Let's put some more hardware on it.  They set more instrumentation on it.  And, sure enough, there ended up to be seven Earth-like planets, just about the size and mass of Earth, orbiting this Jupiter-sized, ultra-cool brown dwarf.

HARI SREENIVASAN:  Now, you say ultra-cool, that doesn't mean it's a cold sun.  It's just not as big or as hot as ours, right?

MILES O'BRIEN:  It's about like Jupiter is to us, OK, cooler and smaller.

HARI SREENIVASAN:  And when we talk about this habitable zone, this Goldilocks, not too cold, not too hot, how do they know that there are planets in this group that exist within that range?

MILES O'BRIEN:  They can measure the radiation off of TRAPPIST-1, this particular ultra-cool brown dwarf, and figure out the zone at which water would remain liquid.  And that's the key.

Everywhere we look on this planet and we find liquid water, we find life.  It doesn't matter where we go.  So, in the hunt for potential alien life, the thought of finding places where there is liquid water is what really intrigues scientists.

So, these planets are a lot closer to TRAPPIST-1 than we are to our sun, but, remember, it's smaller and dimmer.  And they have these very tight little orbits.  And it's quite likely there might be water on some of them.

NASA Announcement Video (38:32)

ASTRONOMY - God's View of Our Solar System

"To Scale: The Solar System"

On a dry lakebed in Nevada, a group of friends build the first scale model of the solar system with complete planetary orbits, a true illustration of our place in the universe.

A film by Wylie Overstreet and Alex Gorosh

THE DARK SIDE - 9th Planet? Home of the 'First Order'

First Order

"We can’t see this possible 9th planet, but we feel its presence" PBS NewsHour 1/22/2016

Excerpt

SUMMARY:  Most of us grew up thinking there were nine planets in the solar system, but that changed when Pluto got downgraded in 2006.  Now there's news that there might be a ninth planet after all.  Researchers have found evidence of a planet with a mass 10 times that of Earth.  Jeffrey Brown talks to Mike Brown of the California Institute of Technology.

JEFFREY BROWN (NewsHour):  Nine planets in the solar system, right?  That’s what most of us grew up thinking.  Well, that ended in 2006, when Pluto was downgraded to a dwarf planet.

But now comes news that there might be a ninth planet after all.  Researchers at the California Institute of Technology (aka Caltech) found evidence of a planet with a mass 10 times that of Earth.

One of the Caltech astronomers, Mike Brown, joins us now.  And I will add that he is also known as the chief culprit in lowering Pluto’s status.  His memoir is titled “How I Killed Pluto and Why It Had It Coming.”

So, sort of making amends here I guess, Mike Brown?

MIKE BROWN, California Institute of Technology:  You know, it’s — I don’t think of it that way.  I think of it as, this is something I have been working at for 20 years, and Pluto was just collateral damage along the way.

JEFFREY BROWN:  All right, so let’s be as clear as we can about what you have done here.  You have not seen this new planet, right?  This is something you surmise.  Explain to us.

MIKE BROWN:  Yes, that’s absolutely right, and it’s important to know that we — no one has actually seen this planet yet.

What we have done is felt it, or, more precisely, we have seen its gravitational effect on the most distant things in the solar system.  And from those gravitational effects, we can tell that it must be out there.  And this is the same way that Neptune, for example, was discovered, by its gravitational effects on Uranus.  So, there’s a long history of this sort of astronomy.

JEFFREY BROWN:  You’re seeing gravitational effects on several — I gather, six small bodies out there?

MIKE BROWN:  There is actually quite a big collection.

There are six that are doing one thing.  There are five more that are doing something else.  And then there’s another eight doing something.  When you put them all together, it’s a pretty big population that are going in directions and moving in ways that they shouldn’t be doing unless there is something organizing the whole pattern.

Solar System 360 Degree Tour!

SCIENCE - Life in Our Solar System

"What two discoveries suggest about life in the solar system" PBS NewsHour 3/6/2015

Excerpt

SUMMARY:  Science correspondent Miles O’Brien joins Judy Woodruff to discuss two space stories that center around the search for life and how it began.  NASA’s Dawn spacecraft arrived in orbit around the dwarf planet Ceres, which scientists believe shows signs of life-sustaining water.  Meanwhile, new research found that Mars once had enough water to cover 20 percent of the planet.

JUDY WOODRUFF (NewsHour):  Let’s close out our Friday with the continuing search, not just for life, but for a better understanding of how life began.

There’s a connection in two space stories today.  This morning, NASA said its Dawn spacecraft arrived in orbit around the dwarf planet Ceres, a journey of more than 300 million miles that lasted more than seven years.  Ceres lies in an asteroid belt between Mars and Jupiter.

And, yesterday, new research found that Mars once had even more water than we realized, enough to cover 20 percent of the planet and larger than our Arctic Ocean.

We’re joined by science correspondent Miles O’Brien.

So, Miles, tell us, what are they looking for on this tiny planet?

MILES O’BRIEN (NewsHour):  Well, wherever you look in the world on our world and you see liquid water, you will find life.  It doesn’t matter where.  You can be in the hot acidic springs of Yellowstone or deep below the ocean in the darkest places.  If there’s liquid water and an energy source, there is life.

And so this is what ties these two stories together.  Dawn is arriving at Ceres.  And there is lots of evidence that Ceres has quite a bit of water, perhaps an ice crust, perhaps even water geysers.  A dwarf planet, Judy, has a molten core.  And so there is reason to believe that there’s heat beneath the surface, which means there could be liquid water, which means there could be things alive there which date back 4.5 billion years.

It’s kind of mind-boggling, but this is like a snowball that’s been in the deep freeze, but it has a liquid core.  And so understanding what’s going on there will tell us a lot about the origins of life here and maybe elsewhere.

NASA - Exploring Ocean Worlds

"NASA discussion in Hampton to explore ocean worlds" by The Associated Press, WAVY.com 11/3/2014

HAMPTON, Va. (AP) — A discussion at NASA’s Langley Research Center in Hampton is exploring oceans at the edge of the solar system.

Officials say Kevin Hand from NASA’s Jet Propulsion Laboratory will present “Ocean Worlds of the Outer Solar System” Tuesday afternoon.

He’ll present a similar program at the Virginia Air & Space Center in downtown Hampton on Tuesday night.

Hand is the deputy chief scientist for solar system exploration at the Jet Propulsion Laboratory in California.

Officials say at least five moons in the outer solar system may have liquid water oceans.  These oceans are considered good candidates for NASA’s search for life beyond Earth.

Hand will explain the science behind why researchers think they know these oceans exist, and what they know about the physical and chemical conditions on these worlds.

SATURN - The Moon Enceladus Has Water

"New report shows water on Saturn’s moon" PBS NewsHour 4/6/2014

Excerpt

HARI SREENIVASAN (NewsHour):  A report published this week in Science magazine offered new remarkable details about the presence of water on one of Saturn’s moons.  It once again stirred talk about the possibility of life elsewhere in our solar system.  For more, we are joined from Los Angeles by David Stevenson of the California Institute of Technology.  He co-authored the article.

So tell us about this moon, Enceladus.  You knew about it, quite a bit about it before.  Tell us what you found and how did you find it?

DAVID STEVENSON, California Institute of Technology:  So we knew already that Enceladus has geysers.  Water coming out of cracks near the south pole.  But we didn’t know what was beneath the surface.  What we’ve now done by tracking the Cassini spacecraft, which is in orbit around Saturn, is figure out that there must be excess mass underneath the ice at the south pole.  And water will do that because water is more dense than ice.  This is an ocean that is about the size of Lake Superior, perhaps even larger and it is about 10 kilometers thick.  So it’s a lot of water.