Category Archives: exploration

The Stars and Planets Ignite Our Dreams

And Make Us Think About What is Possible

A visible light image of the Rho Ophiuchi cloud complex. Courtesy of NASKIES, CC-BY-SA-3.0
A visible light image of the Rho Ophiuchi cloud complex. Courtesy of NASKIES, CC-BY-SA-3.0

What price do you put on stimulating the imagination and scientific interest in someone? I don’t know about you, but I think it’s priceless. Certain events in our history are enough to get us dreaming about the infinite possibilities that lie out there among the other planets and the distant stars and galaxies. Or course, those events did cost something in terms of money and human effort. There’s always a price, a cost, a tradeoff. The payback is knowledge, which comes with both costs, plus the chance to look at places we’ve never seen before. That’s the essence of exploration.

The New Horizonws team celebrates a successful flyby of Pluto.  Image by Carolyn Collins Petersen in the midst of pandemonium.
The New Horizons team celebrates a successful flyby of Pluto. Image by Carolyn Collins Petersen.

New Horizons cost around $700 million, and has certainly inspired people around the world. Worth it? I’d say so. We are supposed to be learning about our universe, using the brains and intellect that evolved along with our bodies. This mission just showed us a world that was long seen only as a point of light. It’s now a place with mountains and craters and icy “continents”, and a “plasma tail’ and a thin atmosphere, and a slew of moons.

Apollo 11 image; Buzz Aldrin's bootprint on the Moon. Courtesy NASA.
Apollo 11 image; Buzz Aldrin’s bootprint on the Moon. Courtesy NASA.

Of course, many people have been celebrating the Apollo 11 landings and the first people to walk on the Moon. The entire Apollo program cost around $25 billion, and its scientific and cultural returns are priceless. We ALL learned something about the Moon, just as we’re all learning something about Pluto with New Horizons. And, about Mars with the missions there. And, about the other planets of the solar system from the many spacecraft we’ve sent out.

We live in an evolving solar system. It hasn’t stopped changing since its formation some 4.5 billion years ago. We’re part of the system, and only recently have we learned to look with scientific eyes at the places that exist in our little part of the galaxy. We’ve learned amazing things through our explorations using both ground-based and space-based instruments. And there’s more out there, if we’re not afraid to go for it.

Is knowing what we know about the solar system and the rest of the universe worth less than the cost of a football stadium? Is it worth less to you personally than the cost of a boutique coffee or a slice of pizza? Is it less important than buying a senator or a whole roomful of them at bargain basement prices? What price do you put on integrity and honesty, scientific curiosity, the urge to KNOW how all this universe works?

You know what MY answer is. Spending money on such exploration benefits people; it creates jobs, stimulates economies and careers, at the same time it teaches us our place in the cosmos. I’d say we got a hell of a deal when we started sending spacecraft out to explore the cosmos. They’re part of us, they’re our eyes and ears on the cosmos, and they are showing us what the universe is made of. Pretty darned good expenditure and use of our time, talents, and energies.

What will we explore next? Exoplanets? There’s more news about those coming soon. How about distant galaxies born in the fires of the first half billion years of the cosmos? Coming up with James Webb Space Telescope. Want to know more about the first stars? Our multi-wavelength observatories in space and on the ground are on the case. Each one of those projects is made up of equipment, sure. But, it’s the people who do the hard work of building, testing, thinking, and sharing the universe with the rest of us. THAT should be worth something to you as you gaze at the stars, look at the pretty pictures, and dream of exploring the cosmos. Shouldn’t it?

A Realm of Planets

More Exoplanet Discoveries

An artist’s concept of the seven planets possibly found orbiting Gliese 667C. Three of them (c, f and e) orbit within the habitable zone of the star. Click to get a larger version. Image courtesy Rene Heller.

The search for exoplanets (also known as extrasolar planets) is a painstaking one. You have to tease out “signals” from the planets, and by that I mean you have to look for evidence of planets in the light from distant stars. If a planet orbiting a star passes in front of its “primary” (its star), that passage dims the light a tiny fraction of a percent. And so, you need a very sensitive light meter attached to your telescope to catch that signal. Likewise, as a planet orbits its primary, it can cause the apparent motion of the star to “wiggle” a bit, and that “signal” shows up in the light streaming from the star. To tease out the wiggles and signals, astronomers break starlight into its component wavelengths (i.e., they take a spectrum) and look for changes in that spectrum. Specific kinds of changes may mean that a planet is affecting the star’s orbit, or causing it to dim down a tiny bit.

There are, however other things that can cause a star to appear to dim down or wiggle in its orbit. For example, it could be a variable star whose light intensity varies a tiny but—just enough to make it seem like a planet is passing between us and the star. Or, the star could be experiencing gravitational perturbations from another nearby star, enough to make it wiggle in its motion. The data not only tell that a planet possibly exists at the star, but also gives astronomers a good idea of what its minimum mass could be.

So, looking for these distant worlds is a complex science. Along the way, astronomers have discovered many new variable stars and even the occasional stellar black holes that affect a star’s light as they pass by. But, often enough, astronomers also find planets. And, that’s when the fun begins. Ground-based observers using large telescopes (larger than you have in your backyard) train their instruments on distant stars with planet candidates and begin the lengthy (often years-long) observations it takes to confirm that a planet is actually orbiting those stars.

Just today, an international team of astronomers, led by Guillem Anglada-Escudé of the University of Göttingen, Germany, and Rory Barnes of the University of Washington announced that they’ve found three “Super-Earth” type planets in the s0-called “habitable zone” of a nearby star. Incredibly enough, this world was previously thought to host two or three planets already, so that brings its possible world count to six or seven. “Super-Earths” are planets that are what they sound like—not more than 10 times more massive than Earth. This is the first time that so many of them have been found orbiting in one system.

The name of the star is GJ 667C, and its actually part of a three-star system that lies in the S-shaped constellation Scorpius. GJ 667C is an M-dwarf star, somewhat fainter than the Sun, and has about a third of the mass that our star does. A star this faint has a habitable zone—the region around it where liquid water could exist on a world—that is very close.  Because the habitable zone is so close to the star, the each planet’s year is much shorter than Earth’s is. They range from 20 and 100 days to go once around the star.  The planets are also very likely “tidally locked,” which means the same hemisphere always faces the star. Luckily astronomers know that life can exist under such conditions.

Since such low-mass stars are inherently faint, their habitable zones—the swath of space that would allow an orbiting rocky planet to sustain liquid water on its surface—lie much closer to the star. The closeness of the habitable zone then makes it easier to find potentially habitable rocky planets around low-mass stars.

In the past few years, astronomers have confirmed at least two planets orbiting this star, and possibly a third one that is still being confirmed. More observations allowed the team to find the new planet candidates. The next steps are to do more observations and detailed study in order to prove that these really are planets. If they are, then there’s a very good chance that this realm of planets will feature worlds with solid surfaces and maybe even atmospheres similar to Earth’s.

That’s the exciting part about planetary searches around other stars. While no one has yet found an Earth analog where life is teeming in oceans or on the surface, the time is drawing near when such a world could be found. It surely does lie out there, somewhere, waiting to be discovered and confirmed.