Question Your World: Can we live on another planet?

Somewhere around 4.5 billion years ago a gigantic ball of mass started to take shape and would eventually become where we all live.  So, the notion of a planet that can harbor life is not a strange one - after all, we happen to live on one.  Are there any other places that are similar? Can we live on another planet?

For the past 200,000 years or so humanity has been here on Earth.  In that time we've figured out how to use fire, harvest crops, change water streams, develop communities, embrace technology and learn about what happens beyond our tiny little cosmic stage.  Not bad for a new species!  Regardless, one thing we have yet to do is gain tactile proof of life existing anywhere else in the universe.

In order to search for life in other parts of the universe one needs to have a basic set of requirements. For example, the functionality of everything we know here on Earth can be traced back to our sun, so to look for other similar situations we must look at other stars (suns).  Well, we also know that the Earth is both rocky and has water.  Those are two more qualifications needed to search for similar conditions.  There's also the matter of temperature.  For example, Mercury is very hot, too hot to hold any life as we know it.  Similarly the moons of Pluto are far too cold for our taste.  Thus the position of the planet relative to its host star is a big deal as well.

Also, keep in mind, looking for planets is no easy task, the stars they orbit are so far away that we only see them as little dots of light in the night sky.  Scientists have tried various methods such as the wobble or transit methods to hone in on and fine tune their understanding of such faint and distant worlds. However, this incredibly complicated process has shown some remarkable data.  For example, in recent years we've gathered enough data to say that there's a really good chance that planets outnumber the stars in our universe.  NASA's official exoplanet list grows all the time and we're up to over 8.8 billion potentially trip-worthy planets in our Milky Way galaxy alone.  Regardless, it takes a lot of factors in just the right balance to allow for comparable conditions to our home here on Earth.

Our Earth is a good size, one that can use its gravitational pull to keep our atmosphere.  Aside from that, our distance from the sun allows for tolerable temperatures and the existence of liquid water.  Those two are very important aspects of planet-hunting.  As of now we're the only place in the known universe to be this size and this distance from our host star.  Well, we were the only place...

Recently, scientists used data from the Kepler Space Telescope and announced the first ever exoplanet discovered to be a similar size and a safe relative distance from their host star.  Kepler 186f is one of 5 planets that orbits its red dwarf star.  How far is it? About 500 light years from here - bring a book, it's a long trip.

So, we may not be able to go visit this place anytime soon, but this discovery is very important as it highlights the possibility of another life-harboring situation out there.  It has taken us around 200,000 years to get from the first time we opened our eyes to today where we can learn about the vast distant reaches of the cosmos.  The work that lays ahead for future generations could yield some remarkable findings on our universe, its creation and perhaps even a better understanding of who or what we are in the grand scheme of things.

Kepler 186f now joins the billions of other exoplanets discovered, but stands out with the distinction that it's the first exoplanet that meets a lot of the special qualifications needed to hold the most mysterious part of our universe, life.

Happy Birthday, Voyager 2!

For an incredible 33 years, Voyager 2 has been our eyes of discovery in the outer solar system and beyond. This venerable spacecraft has been in continuous operation more than 12,000 days, sending us compelling photos and information about the gas giants of the solar system: Jupiter, Saturn, Uranus and Neptune. Now headed into interstellar space beyond the solar system, the spacecraft is still transmitting invaluable data about the solar wind and deep space beyond the planets.

On August 20, 1977, Voyager 2 blasted off from Cape Canaveral, FL on a mission to the giant planets of the solar system. Its sister spacecraft, Voyager 1, was launched a few days later on September 5. Both original missions were intended to study just Jupiter and Saturn. However, both continued sending data beyond those planets, and thanks to these intrepid spacecraft, we have now had a close encounter with every planet in the solar system. (Pluto is now called a “plutoid” and is no longer considered a planet.)

(Just think, the computers on these spacecraft were made in the 1970’s and they are still working! Pretty remarkable, huh?)

Here are a few fast facts about the Voyager mission:

• Explored all giant planets of the outer solar system
• Explored their 48 moons and unique ring systems
• Closest approach to Jupiter - 1979
• Closest approach to Saturn - 1980 (Voyager 1); 1981 (Voyager 2)
• Closest approach to Uranus – 1986 (Voyager 2)
• Closest approach to Neptune – 1989 (Voyager 2)
• Carry a golden record with a greeting from Earth
• Now the most distant human-made object in space (Voyager 1)
• Distance from sun - 17 billion km (Voyager 1); 14 billion km (Voyager 2)
• Signal from Earth takes over 12 hours to reach spacecraft
• Crossed termination shock, where solar wind slows abruptly, in 2004 (Voyager 1); 2007 (Voyager 2)
• May have reached or will soon reach Heliopause or entry into interstellar space
• Currently, 5 teams investigating: Magnetic fields, Low energy charged particles, Cosmic rays, Plasma (Voyager 2), Plasma waves
• May continue to operate and send data until around 2020

Long-lived Voyager has been documented often in fiction and pop culture (remember “V’ger” in the Star Trek movie?). So Happy Birthday, Voyager! May you live long and prosper!

Winter Solstice *

At 12:47 pm today, December 21, 2009, winter begins in the Northern Hemisphere. The first day of winter is called the Winter Solstice; likewise, the first day of summer is the Summer Solstice. The word solstice is derived from Latin and means “sun standing still.” On these two days of the year, the sun’s apparent position in the sky has reached its most southern or northern extreme. Today there will only be 9 hours and 33 minutes of daylight in Richmond, but tomorrow the number of daylight hours will once again begin to increase.
The solstices and the seasons occur because the Earth’s axis is tilted 23.5° relative to its plane of revolution around the sun (see illustration). In the Northern Hemisphere winter, the northern half of the globe is tilted away from the sun; therefore, the sun is low in the sky giving us shorter days and longer nights. At this oblique angle, the sun’s energy is spread over a larger area of the Earth’s surface and thus is weaker than if it was hitting the surface more directly. Also, the sun’s rays must travel through more atmosphere before they reach the Earth’s surface, and some of the solar energy is reflected back into space. In addition, there are less daylight hours to warm the Earth. With all these factors combined, is it any wonder that we have winter weather?
Contrary to what many believe, the Earth is not farther from the sun during the winter. Actually, the Earth is almost at its closest point to the sun at the time of the northern hemisphere’s Winter Solstice. This variation in the Earth’s distance from the sun is small and does not greatly affect the weather; however it does slightly modify the severity of the Northern Hemisphere winters and summers.
While we are experiencing winter, the southern hemisphere is experiencing summer. Our Winter Solstice is the southern hemisphere’s Summer Solstice. If you lived in Rio or Sydney, the winter months would be June through August and the summer months would be December through February.
Here’s some food for thought: what if the Earth’s axis was not tilted? Would we have seasons? What if the axis was tilted more than 23.5°? Or less than 23.5°? What would our seasons be like? How did the Earth get its tilt? All the planets in our solar system have some axial tilt, but they are all different. Why?

*Technical difficulties delayed the posting of this blog entry.

The International Year of Astronomy

By David Hagan, Staff Scientist, Physical Sciences

The International Year of Astronomy 2009 (IYA2009) is a celebration of the 400th anniversary of astronomy as a modern science. In 1609, while Virginia’s tiny colony at Jamestown was struggling to survive, Galileo began looking through his telescope to the heavens for the first time and opening a vast world of wonders. His discoveries and his courageous publications confirmed Copernicus’ model of a sun-centered solar system. Galileo gave us new details of Jupiter’s moons, the phases of Venus, sunspots, and craters and mountains on the moon. That same year Johannes Kepler published "Astronomia Nova," a masterful and rigorous mathematical explanation of the motion of the planets in a sun-centered solar system. Together that year Kepler and Galileo launched not only a new astronomy, but — in some ways — the beginnings of modern science.  

The International Year of Astronomy 2009's mission statement lays out a “global effort initiated by the International Astronomical Union (IAU) and UNESCO to help the citizens of the world rediscover their place in the universe through the day- and night-time sky, and thereby engage a personal sense of wonder and discovery.”

It is a sad fact that, because of the glare of city lights, most of the people in the modern world will never see the wonder of the natural night sky or the Milky Way. Project Globe, a partner in IYA2009, reports that 2 out of 5 Americans, 1 out of 6 Europeans and 1 out of 10 people worldwide have never seen 90 percent of the visible stars in the night sky. With half the world’s population now living in cities, this problem is only getting worse. It is the vision of the International Year of Astronomy 2009 that all people on earth should “realize the impact of astronomy and other fundamental sciences on our daily lives, and understand how scientific knowledge can contribute to a more equitable and peaceful society.”   

Hundreds of IYA2009 programs are under way around the world on a national, regional and local level, with coordinators each country. Throughout the year in the United States coordinating links are being set up among professional and amateur astronomers, science centers and science communicators. Worldwide, 136 countries are involved and well over 140 are expected to participate eventually. The IAU has set up an IYA2009 Web site, www.astronomy2009.org, as the principal IYA2009 resource. The International Year of Astronomy 2009 is endorsed by the United Nations, UNESCO (United Nations Educational, Scientific and Cultural Organization) and the International Council of Science (ICSU).  

One of the great projects of IYA2009 is the Galileoscope. IYA2009 has set a goal to have 100,000 people — each with a hand-held telescope — show the night sky to 100 others, so as to reach 10 million new observers. The Galileoscope is an inexpensive ($15) working hand-held telescope modeled on Galileo’s first telescope. For more information see the Web site https://www.galileoscope.org/gs/ 

In the United States the IYA2009 programs are coordinated through the Web site http://astronomy2009.us/. NASA is a key supporter of IYA2009 programs. Their Web site is http://astronomy2009.nasa.gov/news.htm