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# Seager Equation

EmilyB.Seager Equation

The **Seager Equation** calculator estimates the number of habitable planets in a set of stars based on a number of astronomical factors.

**INSTRUCTIONS:** Enter the following:

- (
**N**) This is the number of stars observed_{*} - (
**F**) This is the fraction of stars that are quiet_{Q} - (
**F**) This is the fraction of stars with rocky planets in the habitable zone_{(HZ)} - (
**F**) This is the fraction of those planets that can be observed_{O} - (
**F**) This is the fraction of planets that have life_{L} - (
**F**) This is the fraction on which life produces a detectable signature gas_{S}

**Habitable Planets (N):** The calculator returns the number of habitable planets.

#### The Math / Science

The **Seager Equation** is a parallel version of the Drake Equation to estimate the number of habitable planets in the galaxy. Where the Drake Equation predicts the number of alien civilizations with radio technology, Seager has revised the Drake equation to focus on simply the presence of any alien life detectable from Earth. The equation focuses on the search for planets with biosignature gases, gases produced by life that can accumulate in a planet atmosphere to levels that can be detected with remote space telescopes.

The Seager Equation formula is:

N = N_{*} • F_{Q} • F_{(HZ)} • F_{O} • F_{L} • F_{S}

where:

- N = number of planets with detectable signs of life
- N
_{*}= number of stars observed - F
_{Q}= fraction of stars that are quiet - F
_{(HZ)}= fraction of stars with rocky planets in the habitable zone - F
_{O}= fraction of those planets that can be observed - F
_{L}= fraction of planets that have life - F
_{S}= fraction on which life produces a detectable signature gas