Answer to Question 1
A planet orbiting another star is called an extrasolar planet. Such a planet would be quite faint and difficult to detect so close to the glare of its star. But there are ways to find these planets. To see how, all you have to do is imagine walking a dog.You will remember that Earth and its moon orbit around their common center of mass, and two stars in a binary system orbit around their center of mass. When a planet orbits a star, the star moves very slightly as it orbits the center of mass of the planet-star system. Think of someone walking a poorly trained dog on a leash; the dog runs around pulling on the leash, and even if it were an invisible dog, you could plot its path by watching how its owner was jerked back and forth. Astronomers can detect a planet orbiting another star by watching how the star moves as the planet tugs on it.
Answer to Question 2
Infrared astronomers have found cold, low-density dust disks around older stars such as Vega and Beta Pictoris. Although much younger than the Sun, these stars are on the main sequence and have completed their formation, so they are clearly in a later stage than the newborn stars in Orion. These low-density disks generally have even lower-density inner zones where planets may have formed. Such tenuous dust disks are sometimes called debris disks because they are understood to be dusty debris released in collisions among small bodies such as comets, asteroids, and Kuiper Belt objects.
Planets, Earth and Moon
This modified model of Easton’s systems theory puts government decision makers as the source of pol
Historian James Merrell notes several errors in Benjamin West’s famous 1771 painting, William Penn’s
What are examples of ideal forms?
Relative Sizes of Dwarf Planets and Earth
Under ideal conditions, a single cell of the bacterium E. coli would divide every 20 minutes to ...