« previous next »

Author Question: How do we know that planets exist around other stars? How many such planets have been detected to ... (Read 32 times)

penguins

  • Hero Member
  • *****
  • Posts: 903
on: Jul 14, 2018
How do we know that planets exist around other stars? How many such planets have been detected to date?
 
  What will be an ideal response?

Question 2

What factors in the Drake equation are we capable of estimating today?
 
  What will be an ideal response?


juiceman1987

  • Sr. Member
  • ****
  • Posts: 316
Reply #1 on: Jul 14, 2018
Answer to Question 1

We have witnessed the effects of extrasolar planets on their parent stars, both in the periodic wobble of the parent star caused by the gravitational tug of the planet, and in the periodic dimming of light coming from the star as the planet passes in front of it. As of this writing, over 400 planets in 324 star systems have been discovered. For an up-to-date count, go to NASA's Planet Quest New Worlds Atlas Search, which can be found here: http://planetquest1.jpl.nasa.gov/atlas/atlas_index.cfm.
Or, try the Extrasolar Planets Encyclopedia at: http://exoplanet.eu/

Answer to Question 2

We can estimate Ng, the number of stars in a galaxy; fp, the fraction of stars that have planets; and ne, the number of Earthlike planets per planetary system. Currently, fl, the fraction of habitable planets on which life evolves; fi, the probability that life will evolve to a steady state; fc, the probability that intelligent life will develop the capacity to communicate over long distances; and fL, the fraction of a planet's lifetime during which it supports a technological civilization, are not well constrained.


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
« previous next »
 

Did you know?

IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.

Did you know?

Since 1988, the CDC has reported a 99% reduction in bacterial meningitis caused by Haemophilus influenzae, due to the introduction of the vaccine against it.

Did you know?

Drying your hands with a paper towel will reduce the bacterial count on your hands by 45–60%.

Did you know?

It is widely believed that giving a daily oral dose of aspirin to heart attack patients improves their chances of survival because the aspirin blocks the formation of new blood clots.

Did you know?

It is believed that the Incas used anesthesia. Evidence supports the theory that shamans chewed cocoa leaves and drilled holes into the heads of patients (letting evil spirits escape), spitting into the wounds they made. The mixture of cocaine, saliva, and resin numbed the site enough to allow hours of drilling.

The Pleiades, an open cluster of stars in the constellation of Taurus. The Pleiades, an open cluster of stars in the constellation of Taurus.
Internal structures of main sequence stars, convection zones with arrowed cycles and radiative zones Internal structures of main sequence stars, convection zones with arrowed cycles and radiative zones
The Magnetic Fields of Five Planets The Magnetic Fields of Five Planets
Current Positions of Known Dwarf Planets and SSSBs in the Outer Solar System Current Positions of Known Dwarf Planets and SSSBs in the Outer Solar System
Breathe Carolina & Shanahan ft. Haliene - Stars & Moon Breathe Carolina & Shanahan ft. Haliene - Stars & Moon
SBTRKT - Look at Stars Ft. Sampha SBTRKT - Look at Stars Ft. Sampha
Video: Random alignment at Metaphase I Animation

For a complete list of videos, visit our video library