July 01, 2009, Victoria, British Columbia
"Finding another Earth would be like finding the Holy Grail," says Dr. Christian Marois, an NRC astrophysicist who never tires of scanning the skies for unidentified planets. When scientists like him find proof of exoplanets - planets that orbit a star other than our own Sun - they can't help but be over the moon.
Dr. Marois has good reason to be excited these days. He and his team of Canadian, U.S. and British astronomers were recently in the limelight for capturing the first-ever direct images of another solar system within our own galaxy, the Milky Way. These infrared images are definitive proof that the three giant planets - each roughly 10 times the mass of Jupiter - orbit a star known as HR8799, in the constellation of Pegasus. The team confirmed their infrared images through advanced instrumentation and image-processing technology, using the Gemini North and Keck telescopes on the summit of Mauna Kea in Hawaii.
A 3D representation of the HR 8799 planetary system (left) and the solar system (center) in the Milky Way.
"By comparing infrared images generated in different years, we have shown that the three planets are all orbiting around the star, proving they are associated with it and are part of a solar system," says Dr. Marois. "This solar system is fairly close to our own; HR8799 is faintly visible to the eye and is only 130 light-years away."
2009 is the International Year of Astronomy and the 400th anniversary of the telescope. At the turn of the 17th Century, Galileo Galilei used a one-inch telescope to confirm the phases of Venus and discover the four largest satellites of Jupiter - a mini solar system. It has taken 400 years of telescope innovations for mankind to produce real images of another solar system.
Although these are the world's first real images of another solar system, it's no surprise that such systems exist alongside our own. "For a long time, we've known that there are other solar systems and have relied on indirect methods to detect exoplanets," says Dr. Marois. "But, because of the limitations of our instrumentation, we've never been able to discern such planets directly."
It's far easier to see a star than to see a planet orbiting that star. That's because a planet, unlike a star, has no internal source of energy to maintain its temperature. As it ages, it cools and becomes dimmer and harder to see compared to its parent star, which continues glowing brightly. In addition, the light from the parent star causes a glare that washes the planet out.
What marks the accomplishment of Dr. Marois and his team is their innovative imaging technique, which allowed them to offset optical "turbulence" by measuring the atmospheric and telescope distortions and removing them. This yielded images that prove these planets' existence and some of their physical characteristics, such as their size, temperature and mass.
Dr. Marois and his colleagues at the NRC Herzberg Institute of Astrophysics are passionate about their science. What drives him to identify and characterize exoplanets? "It's all about understanding how planet Earth came to be," he says. "If we can find a planet with life-supporting conditions in another solar system, we could re-examine the theories about our own planet's formation and have a far better idea of the conditions that led to life here."
