The Planet/Universe Flashcards
What are the two most important factors that make our planet able to sustain life?
Liquid water (and lots of it).
An energy source (the sun). The planet is within the habitable zone of a star.
What are the many factors that contribute to earth being able to sustain life? Try naming 5 of 12 factors.
Lots of water.
Habitable zone.
Consistent reasonable temp. 15 °C
Rocky planet.
Stable atmosphere (that’s not toxic).
Magnetosphere (deflects radiation + solar wind).
The moon (stabilize’s rotation, tides).
Stable, solitary sun.
Ozone (protects from UV).
Large outer planets (attract meteors).
Stable solar system.
Location in the Milky Way (away from center = fewer collisions or radiation).
What is the habitable zone of a star?
Not close enough to fry and not far enough for all water to be ice. Not too hot, not too cold, just right!
What is a nebula?
A cloud of gas or dust in space. Where stars are born or the remains of dead/dying stars. They also create the elements of life.
What is a main sequence star?
One that converts hydrogen to helium in its core; releasing tons of energy. These stars are in a state of hydrostatic equilibrium.
What are neutron stars and Supergiant stars?
Neutron stars explode.
Supergiants are super giant.
They are unstable, burning fast and bright, but dying young.
When/where were the elements hydrogen and helium formed?
In the Big Bang!
Where do our elements come from?
Mostly from large stars (nuclear fusion in the interior of stars) and supernovae (stars exploding).
Are we all made of star stuff?
Yes!! 💫
What is an exoplanet?
A planet that orbits a star other than the Sun. It’s not part of our solar system.
When did scientists start discovering exoplanets? How many have they discovered?
In the 1990s.
Well over 5,000.
How far away is the closest potentially habitable exoplanet?
Proxima b is approximately 4 light years away.
What is a light year?
A measure of distance equivalent to the distance that light can travel in one year (approx. 9.46 trillion km)
What is the purpose of the Drake equation and what can we learn from it?
A formula to estimate how many extraterrestrial civilizations may exist in the Milky Way.
“[It’s] likely that we are not the only time and place that an advanced civilization has evolved.”
What were the conditions on the early planet?
Too hot for liquid water; toxic atmosphere from volcanoes; earth’s crust was thin and cooling, no ozone = lots of UV, lots of lightning.
When did seas on earth form? Were they salt or fresh water?
By about 3.85 b.y.a.
All water was fresh.
How did the seas become salty?
By leaching of minerals from the continents and sea floor. It may have taken 100 million years or so to become salty.
How many mass extinctions have there been?
5 mass extinctions and we know that we are now in the midst of the 6th.
When did life begin to flourish on earth (although it had existed long before this)?
Around 600 million years ago when life colonized land.
What is the Pale Blue Dot?
An image taken by the Voyager I space probe as it was leaving the solar system in 1990. (image requested by Carl Sagan).
