Kepler was launched on March 7, 2009 to monitor over 145,000 stars in the constellation Cygnus. Analysis of fluctuations the brightness of these stars will help identify extrasolar planets and determine how many Earth-sized planets are in or near the habitable zone of their star.

Dr. Steffen will discuss the technology and science of the Kepler mission and explain how the mission helps to address questions about how our Earth fits among the population of planets in our galaxy. He will also explain how Kepler’s findings will pave the way for future research missions to look for signs of life on other planets. Following his presentation, audiences will see Extreme Planets, an original Clark Planetarium production, featuring the composition and significance of extrasolar planets to the field of astronomy.

Dr. Steffen currently resides in Illinois, but has lived in Utah. He graduated from Weber State University in 2000 and returns to the area for visits. “Since I have a connection to the Wasatch Front, I’m glad to have the 
opportunity to present this information to the residents of Salt Lake 
City. Most of the scientific community that studies exoplanets is located 
on the coasts and near major observatories.  This will be an 
opportunity for residents to hear what is happening in an important field that has fewer direct ties to Utah,” he said.

“The discovery of other Earth-like planets in our galaxy is a fascinating topic of discussion,” said Clark Planetarium Director, Seth Jarvis. “We’re delighted to offer the public an opportunity to learn about Kepler’s findings first-hand from someone who is directly involved at the cutting edge of this research.”

Clark Planetarium’s mission is to create and present stimulating educational programs that effectively share astronomy and space exploration information with Salt Lake County residents, Utah students, educators and families and visitors from around the country and the world. Additional information on this event can be found on the Clark Planetarium website.

Tickets are $1 at the planetarium’s ticket desk or $2 online.

Due to the technical nature of this presentation, it is not recommended that children under 8 years of age attend.

Date: Feb. 8, 2010

Time: 7 – 9 p.m.

Location: Hansen Dome Theatre

I keep a little dashboard widget from NASA on my Mac at home that keeps a running score on the number of extra-solar planets that have been discovered.  When I left for work this morning the exoplanet tally stood at 374.  As I write this post, that number has zoomed past 400.

Wow!

Think about that for a moment.  We now know of 50 extra-solar planets for every one planet in our solar system.  That 50:1 ratio is only going to get more lopsided as research continues.

I wrote this past summer about how astronomers hunt for exoplanets here.

Pay particular attention to the Kepler research spacecraft currently orbiting Earth.  This robotic telescope is right now simultaneously scanning about 100,000 stars in the vicinity of the constellation Cygnus on a hunt for earth-like planets.

Clark Planetarium will host a “Searching for other Earths” lecture this coming February by an astronomer working on the Kepler mission – keep an eye on the planetarium web site for details.

What we’ll do with scientific evidence of truly earth-like worlds in our galaxy is a fascinating topic to think about.

What would you do with certain knowledge of an earth-like planet a few hundred light years from us?  I can imagine lots of things – but shrugging my shoulders and saying “so what?” isn’t one of them.

When (not if) genuinely earth-like planets are discovered, that won’t mean UFOs are really alien spaceships.  The distances between us and any exoplanets are on the order of hundreds or thousands of light years.  In-person visits are out of the question – the distances involved are overwhelming.

If you could somehow make a spaceship travel ten thousand times faster than the fastest space vehicle ever launched, then a journey to one of the nearest of these recently discovered exoplanets would still require hundreds of years.

“Warp speed” is fine for sci-fi entertainment, but in the real world there are implacable laws of physics and mathematics that dictate why travel at the speed of light is impossible:

• To travel at the speed of light you become more massive than the entire universe,
• Your width shrinks to zero and you become two-dimensional,
• Time stops completely for you and the universe ages out of existence in an eyeblink, and oh-by-the-way,
• Your mathematics must be able to produce real-numbers answers for equations that involve dividing by zero.

You want to imagine going faster than light? (Scotty!  We need full power to the warp drive, NOW!)

Good luck with that.  Faster-than-light travel requires mathematics that produce real-number solutions to equations that involve taking the square-roots of negative numbers (go ahead and try that with your calculator).  Then there’s the whole cause-precedes-effect relationship being violated by superluminal speeds to deal with.  Good luck with that, too.

But don’t stop thinking about how to get to one of these soon-to-be-discovered earth-like exoplanets just because I’m throwing a few division-by-zero stumbling blocks in your path.  If you can actually, demonstrably and “for-reals” figure out a way to get to a habitable world orbiting Epsilon Eridani in less than ten years then fame and wealth beyond imagination are yours and I’ll be the first to applaud your success.

(But please  – don’t send me your ideas for a warp-drive.  I’m not in a position to evaluate such things.)

Great question!

To date astronomers have discovered well over three hundred planet orbiting stars other than our own Sun, and that number is growing rapidly. We call these planets orbiting other stars “exoplanets.”

Think about that for a minute… Today we are aware of forty times more planets outside of our solar system than we know of inside our solar system.

There are several methods used to discover exoplanets, but one of the most commonly used methods involves looking at how the gravitational attraction between the exoplanet and its central star causes the star to wobble as the exoplanet orbits.

Even though most stars are many thousands of times more massive than any planet that orbits them, a really massive planet, such as Jupiter (which is more than 300x the mass of Earth), can exert enough of a gravitational tug on a smallish star to cause the star to shift back and forth a tiny but measurable amount as the planet moves around the star.

Starlight can tell you a lot about a star. By carefully studying a star’s light astronomers can determine the star’s chemical makeup, temperature, mass, size and age. By combining the information gained from the star’s spectrum with a few other clever observations astronomers can also determine the star’s distance from Earth and its velocity through space.

All that information can be found by analyzing the light coming from a star. As an example, here’s an image of our Sun’s spectrum:

All those little dark lines spread out over the different colors of sunlight represent chemical elements that are present in the Sun’s atmosphere.

If a star is approaching us the lines are shifted slightly towards the blue end of the spectrum. If the star is receding from us the lines are shifted slightly towards the red end of the spectrum.

Gravity works in both directions between a star and any exoplanet in orbit around it. The star tugs on the exoplanet, and the planet tugs back on the star. When astronomers find a star that periodically appears to be approaching and then receding from Earth they know they’re looking at a star that’s doing a cosmic do-si-do with one or more exoplanets in orbit around it.

The magnitude, duration, and complexity of the periodic changes in the star’s spectrum tells astronomers the mass, distance and period of orbit of the exoplanet.

By knowing the exoplanet’s mass and distance from its star, and the temperature, mass and brightness of the central star itself, astronomers can estimate the exoplanet’s size, composition and surface temperature.

Another way to discover planets is to observe the slight dimming of a star’s light when an exoplanet happens to travel directly in front of the star as seen from Earth.

Even though this is roughly the equivalent of detecting changes in a car headlight’s brightness from a mile away as a gnat crawls across the headlight, astronomers have instruments that are indeed sensitive enough to make this kind of measurement.

This is a very exciting time for the study of exoplanets. NASA has recently launched the Kepler Mission, an orbiting spacecraft that will study stars to look for the passage of Earth-sized planets in front of their primary stars.

Many exoplanets have been discovered using this technique, but one at a time. Kepler is going to look at more than 100,000 stars simultaneously.

Even more exciting, as the exoplanet passes in front of its primary star, the light of the star passes through any atmosphere the exoplanet might have, and carries the spectral chemical signatures of the atmosphere along with the rest of the star’s spectrum to Earth. By subtracting the spectrum of the star plus planet from the spectrum of the star alone, it’s possible to study the chemistry of the exoplanet’s atmosphere.

Very cool!