Exoplanets: Introduction (02:01)
Scientists believe they are getting closer to discovering another inhabited planet. Technological challenges include vast distances and mysteries about life on Earth.
Existence of Extraterrestrial Life (03:32)
In 1990, the Voyager I space probe photographed Earth from the solar system's edge. Researchers discuss the possibilities that our planet is not unique in the Universe. Frank Drake's equation attempts to measure the number of civilizations in the Milky Way.
Idea of an Infinite Universe (03:29)
Since the 1970s, SETI telescope arrays have searched for extraterrestrial radio signals. Since Edward Hubble confirmed that Andromeda is a separate galaxy, astronomers have understood the existence of millions of galaxies. Hear why Earth may be premature in receiving a response.
Studying the Universe (03:58)
Astronomers cannot bring the universe into the lab. Learn about the use of spectroscopy to study objects in space. Visit the Gran Telescopio Canarias, the world's largest telescope, and hear how its mirrors gather photons from distant galaxies.
Discovering 51 Pegasi b (06:49)
Hear how Michel Mayor and Didier Queloz used radial velocity to find the first exoplanet in 1995. To their surprise, it was larger than Earth and closer to its star, with a year of just four days.
Transit Photometry (03:06)
After 51 Pegasi b, scientists began searching for life supporting exoplanets. Hans Deeg's team used a method detecting star dimness from planets passing in front of them. In 2009, the Kepler space telescope confirmed the existence of transit detected exoplanets.
In 2005, a precision spectrograph was developed to detect smaller planets through radial velocity. In 2004, scientists discovered the first directly visible exoplanet. Hear how they rendered its starlight "invisible" and used adaptive optics to circumvent Earth's atmosphere.
Proximal Exoplanet Search (01:55)
Hear advantages and disadvantages of using direct images. Combining radial velocity and transit photometry reveals a planet's characteristics. New projects use radial velocity and focus on stars closer to the Sun.
Star Systems Suited for Life (02:21)
Stars are classified mainly by temperature. Planets are unlikely to form near large, hot stars with shorter lives. Scientists are looking for yellow dwarves like the Sun; Earth-like planets supporting liquid water are difficult to find.
Habitable Zone (02:59)
The search for another Earth depends on the presence of water, starlight emitted, starlight wavelength, planet surface gravity, and planet atmosphere. Hear how atmospheric conditions determine surface temperature and pressure. Habitable planets range in size from Mars to 1.5 Earths.
Red Dwarf Systems (04:03)
Life is adaptable; microorganisms can survive in harsh environments. To find an Earth-like planet within a habitable zone, scientists look at smaller and colder stars—the majority in the galaxy. Red dwarves are long lasting but highly active and capture planetary rotation.
Surveying Earth-like Planets (03:10)
Scientists are monitoring a selection of 300 stars using the CARMENES instrument. This detects exoplanets and reveals the chemical composition of their atmospheres. Technology detecting planet surfaces will be developed over the next decade.
James Webb Space Telescope (02:22)
Planetary systems with short transits allow researchers to detect planetary chemical composition and atmospheric components supporting life. NASA's mirrored satellite is more powerful than the Hubble Telescope and will capture infrared light.
Plato Mission (02:17)
Willy Benz directs the CHEOPS telescope studying known exoplanets. In 2026, the ESA will launch a space observatory analyzing light curves from over 200, 000 stars and searching for planetary transits. Planets will be confirmed through radial velocity.
Espresso and ELT (03:40)
At the Geneva Observatory, a powerful spectrograph detects radial velocity of 0.1 meters per second. The European Southern Observatory's Extra Large Telescope is under construction for completion in 2024. It will capture direct images of exoplanets and help detect atmospheric elements.
Proving Extraterrestrial Life (03:39)
Chemistry evolved for thousands of millions of years to produce intelligent life on Earth. Scientists have been surprised by exoplanetary diversity and abundance. Many believe microorganisms exist on other planets, but finding conclusive evidence will be challenging.
Credits: Searching for Life: On the Trail of Exoplanets (00:34)
Credits: Searching for Life: On the Trail of Exoplanets
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