The Rare Earth: There aren’t too many places like our planet.. Everything is “just right” for life to exist

Earth has the 5 key factors that make our planet ideal for life Perfect proximity to the sun- for warmth and photosynthesis Perfect Planet Size/Gravity- to keep us and our atmosphere grounded Atmosphere Composition– for protection and life processes Water- for life processes Carbon and other important elements- the basics of organic compounds

What does Goldilocks have to do with Science?? For life to exist on a planet, the following things have to be just right….. Temperature Size Composition

The Goldilocks Principle The Goldilocks Principle states that something must fall within certain margins, as opposed to reaching extremes. It is used, for example, in the Rare Earth hypothesis to state that a planet must neither be too far away from, nor too close to the sun to support life. Either extreme would result in a planet incapable of supporting life.[1] Such a planet is colloquially called a "Goldilocks planet".[2][3] ---- Wickipedia Rare Earth hypothesisplanetsun[1]Goldilocks planet[2][3]

Earth as the Standard Earth is JUST RIGHT!!! Earth is JUST RIGHT!!! When looking for planets that could harbor carbon based life forms, scientists use Earth as the standard unit When looking for planets that could harbor carbon based life forms, scientists use Earth as the standard unit 1 M mass, and 1 M mass, and 1 AU distance. 1 AU distance. 1= earth size 1= earth size As far as we are concerned the closer to 1 the better!! As far as we are concerned the closer to 1 the better!!

Earth as the Standard planets less than earth 1> p planets greater than earth 1<p Ex… a planet with.8M earth has a mass that is 80% of earth’s mass; 1 AU (astronomical unit) is the distance from the Sun to our Earth

Ideal Temperature Temperature range of 15°C to 115°C. The Zone of Habitability is based on the temperature zone for a star. Different star types have different spots for the zone of habitability. For a yellow, medium sized star (like our sun), the zone of habitability is between.84 AU and 1.7 AU

As the size and Temperature of stars change, so does the zone of habitability

The Zone of Habitability for a star like our sun is between.84 AU and 1.7 AU Temperature: The Zone of Habitability for a star like our sun is between.84 AU and 1.7 AU

Temperature: As the size and temperature of stars change, so does the zone of habitability

Temperature: Where in the galaxy is the right star??- Go GREEN! Far from the core Far from the core Intense radiation from its huge black hole Intense radiation from its huge black hole Too many stars, will disrupt planets’ orbits Too many stars, will disrupt planets’ orbits In from the rim In from the rim Rim stars tend to be older & cooler Rim stars tend to be older & cooler Outside galaxy arms Outside galaxy arms Too many stars, will disrupt planets’ orbits Too many stars, will disrupt planets’ orbits Scientists Classify stars in different classes based on their age and color. Our sun is a class “G” Star. Scientists believe that Classes “F,” “G,” and “K” are most likely types of stars to support a living planet.

Temperature = Liquid Water The Habitable Zone Life seems limited to a temperature range of 15°C to 115°C. Life seems limited to a temperature range of 15°C to 115°C. In this range, liquid water can still exist under most conditions. In this range, liquid water can still exist under most conditions. This is the primary rule behind the principle of the “Habitable Zone” This is the primary rule behind the principle of the “Habitable Zone” Habitable Zones: are determined by the size of a planet’s star and planet’s distance from it.

Turning Temperature Rotation (planet’s spin on axis) and Revolution (orbit around star) affect how evenly heated and cooled a planet is. Rotation (planet’s spin on axis) and Revolution (orbit around star) affect how evenly heated and cooled a planet is. Extreme differences in Rotation or Revolution, from that of Earth’s can cause adverse conditions that could inhibit life. Extreme differences in Rotation or Revolution, from that of Earth’s can cause adverse conditions that could inhibit life.

Ideal Size Mass:.5 M earth - 10 M earth Radius:.8 R earth R earth

2. Size = Gravity= Atmosphere Planets too small will not have enough gravity to hold an atmosphere! Planets too small will not have enough gravity to hold an atmosphere! Planets too large can have an atmosphere too thick to support life as we know it. Planets too large can have an atmosphere too thick to support life as we know it. A habitable planet would also need to have the right type of atmospheric chemistry. (Nitrogen, carbon dioxide, & free oxygen similar to what we have on earth) (see composition next!) A habitable planet would also need to have the right type of atmospheric chemistry. (Nitrogen, carbon dioxide, & free oxygen similar to what we have on earth) (see composition next!)

Size Atmosphere on Habitable Planets Earth’s atmosphere is about 100 miles thick. It: Earth’s atmosphere is about 100 miles thick. It: Keeps the surface warm. Keeps the surface warm. Protects it from radiation Protects it from radiation Protects it from small to medium sized meteorites. Protects it from small to medium sized meteorites. Provides chemicals needed for life, such as Nitrogen and Carbon Dioxide. Provides chemicals needed for life, such as Nitrogen and Carbon Dioxide. Earth and Venus are the right size to hold a sufficient sized atmosphere. Earth and Venus are the right size to hold a sufficient sized atmosphere. But their composition is very different But their composition is very different

Composition Minimum Elements Required: C, H, O Crust rich in rocks, minerals and metals Water oceans compounds and molecules required: liquid H 2 O; O 2 ; minimal CO 2 &

3: Composition Requirements: The Right Combination for ‘Our Kind’ of Life Earth’s Main Elements: ¡SPONCH! Carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus Carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus Trace elements, like iron (Fe) & magnesium (Mg) Trace elements, like iron (Fe) & magnesium (Mg) - Liquid water -Atmosphere that has free oxygen, and allows light penetration for energy

Composition:The right Combination Atmosphere %

Composition:Greenhouse Gas Comparisons

Space Exploration Studying space is difficult because of its vast distances and lack of approproate Temperature, composition, and gravity for human survival. Studying space is difficult because of its vast distances and lack of approproate Temperature, composition, and gravity for human survival. Humans have to make lots of adjustments when venturing into space to explore Humans have to make lots of adjustments when venturing into space to explore

Rockets Rockets have to supply energy, appropriate pressure and oxygen to its occupants. The strict pressure and air requirements are similar to a submarine! Rockets have to supply energy, appropriate pressure and oxygen to its occupants. The strict pressure and air requirements are similar to a submarine!

International Space Station Once in space, astronauts need food, and oxygen as well. Once in space, astronauts need food, and oxygen as well. Plants are being studied in space in efforts for them to eventually help supply both of these things to our astronauts! Plants are being studied in space in efforts for them to eventually help supply both of these things to our astronauts!

Modeling space Because space is so large and largely unknown making models are often difficult. Because space is so large and largely unknown making models are often difficult. Size and distances are especially hard to represent in classrooms Size and distances are especially hard to represent in classrooms For example, while the model below represents accurate size differences, all of the pieces could not be hung in the same classroom to accurately show distances!! For example, while the model below represents accurate size differences, all of the pieces could not be hung in the same classroom to accurately show distances!!