Until the middle 1990s, the practical study of the origin of planets focused
our single known example—the solar system.. Although there had been a great deal of speculation about planets circling other stars, none had actually been detected. Logically enough, in the absence of data, most scientists assumed that our own system was likely to be typical. They were
for a big surprise.
For centuries, astronomers have dreamed of finding planets around other stars, including other planets
Earth. Direct observations of such distant planets are very difficult,
. You might compare a planet orbiting a star to a mosquito flying around one of those giant spotlights at a shopping center opening. From close up, you might spot the mosquito. But imagine viewing the scene from some distance away—say, from an airplane. You could see the spotlight just fine, but what are your chances of catching the mosquito in that light? Instead of making direct images, astronomers
relied on indirect observations and have now succeeded in detecting a multitude of planets around other stars.
In 1995, after decades of effort, we found the first such exoplanet (a planet outside our solar system) orbiting a main-sequence star, and today we know that most stars form with planets. This is an example of how persistence and new methods of observation
the knowledge of humanity. By studying exoplanets, astronomers hope to better understand our solar system in context of the rest of the universe.
Most exoplanet detections are made using techniques where we observe the effect that the planet exerts on the host star. For example, if the planet's orbit is properly aligned, a planet will periodically cross in front of the star,
the brightness of the star to dim.
The best possible evidence for an earthlike planet elsewhere would be an image. After all, “seeing is believing” is a very human prejudice. But imaging a distant planet poses a considerable
indeed. The planet is swamped by the blaze of radiation from its parent star. Even today, the best telescope mirrors’ optics have slight
1. What assumption did scientists make before exoplanets were discovered?
2. What does the mosquito comparison mainly emphasize?
3. Why do astronomers often prefer indirect detection methods?
4. What is suggested about the 1995 discovery?
5. Which statement best describes how planets are often detected?
6. Why is direct imaging of exoplanets difficult?
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