STATES CHRONICLE – International astronomers led by researchers from the University of Hertfordshire discovered four planets orbiting a nearby Sun-like star, tau Ceti. Two of these are possibly habitable planets, according to reports. Radial velocity, a technique using spectroscopy to measure the wobble in a star’s motion due to planets orbiting it, produced these finding. This discovery is an exciting step in the search for habitable planets, especially ones close enough to Earth for future interstellar travel.
Locating Possibly Habitable Planets
Tau Ceti, located just 12 light years from our planet, is in the constellation Cetus. In galactic terms, this is considered a stellar nearby neighbor. Tau Ceti is similar to our solar system’s Sun in size and brightness. This seemingly increases the probability that an orbiting planet could be habitable. NASA defines habitable planets as ones where liquid water can exist and pool. The four planets identified have orbits of 20, 49, 160, and 642 days.
The 160-day orbit planet is similar to Mars, on the hot side of possibly habitable planets. In contrast, the 642-day orbit planet compares to Venus and is on the cold end of planets able to support life.
The study project was truly international. Data collection required advanced spectrographs at the European Southern Observatory, Chile and the W. M. Keck Observatory, Hawaii. Fabo Feng, a research fellow at the University of Hertfordshire, England was the lead author, and his co-author was Steven Vogt, a professor of astronomy at the University of California, Santa Cruz. Their article, “Color difference makes a difference: our planet candidates around tau Ceti,” has been accepted for publication in the Astronomical Journal.
NASA reports that in the past 20 years, more than 3000 planets orbiting distant suns have been identified. However, few of these are possibly habitable planets. Two of tau Ceti’s planets can potentially meet the requirement for sustaining liquid water. An issue is the amount of stellar nearby debris which could strike the planets. Still, some consider that even with these concerns, the tau Ceti system may be an initial target for interstellar colonization.
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