Module 1: Planet Earth Flashcards
Planet Earth, the solar system and minerals
What happened during the big bang
The universe blinked violently into existence 13.77 billion years ago. It involved a sudden expansion of matter, entry, and space from a single point. It is still happening; the universe is still expanding.
Solar System Formation
- Collapse a nebula - dust within the patch comes together first drawn by static electricity, then by gravity.
- A star forms from the collapsed nebula and the rest of the dust and gas becomes a protoplanetary disk.
- Build some planets through accretion - drawn together, again, by static electricity, then gravity
How was the moon formed, how do we know?
A Mar’s-sized planet, Theia, collided with Earth. Theia’s metal core merged with Earth’s core. The debris from the outer silicate layers was flung into space. The material formed, like a planet does, to create the moon. We have evidence of other impacts, including the Barringer Crater, Arizona, and Maniitsoq “crater” in west Greenland. The collision gave earth it’s tilt and created our seasons
Progress in the hunt for habitable-zone planets outside our solar system
Kepler - find earth-like planets and estimate how many are in our galaxy. Found billions of Earth-sized planets in the Milky Way, about 5% in the habitable zone.
TESS Mission - survey the brightest stars near Earth for exoplanets. 440 confirmed, 7,130 candidates – likely 80% ish will be confirmed planets.
James Webb Space Telescope - Looking for biosignatures or signs that life exists
How are scientists looking for life on other planets?
By using transits to analyze the wavelengths of light that pass through a planet’s atmosphere and the ones that are absorbed, scientists can extrapolate what the atmosphere is made of. Biosignatures include:
o Oxygen - photosynthesis
o Ozone - lots of oxygen over time
o things that can’t be made abiotically
o Carbon dioxide – animal breathing
o Methane – bacteria and animal farts
o Dimethyl sulfide – phytoplankton
Exoplanets
Planets that orbit a star other than Earth’s sun
Big Bang Theory
The theory that the universe started with an explosion approximately 13.77 billion years ago
Light Years
The distance that light can travel in one year (94,607 x 1012 km)
Cosmic microwave background
The radiation left over from the early stage in the development of the universe at the time when protons and neutrons were recombining to form atoms.
Galaxies
A gravitationally-bound system of stars and interstellar matter
Doppler effect
when a thing emits waves, sound, light, or ripples in the water. When the thing moves a stationary observer will see/hear the waves approaching them at a higher frequency and if the object is moving away the waves will appear at a lower frequency. Example: swimming duck in the water, the waves in front of the duck are bunched closer together, and the waves behind the duck are spread further apart
Red Shift
If a star is moving towards you, you will see it at a higher frequency or more blue. If a star is moving away from you, the light will appear to shift to the red spectrum.
wavelength
The distance between the crests of two waves. Wavelengths of light are seen as color. Wavelengths of sound are heard as pitch.
Solar System
A star and the planets surrounding it
Nebula
a giant cloud of dust and gas in space, potentially thrown out by the explosion of a dying star (supernova). Also a region where new stars are beginning to form.
Protoplanetary disk
When a star forms from a collapsed nebula, the remaining dust and gas create a disk that rotates around the star. This is where planets form.
asteroid belt
contains bodies of rock and metal ranging from meters to hundreds of meters
accretion
particles gather together, first with static electricity, then gravity, eventually forming larger and larger masses that may become planets
differentiation
4.5 billion years ago, when the earth was primarily molten, it was also bombarded with collisions, further heating it. It’s gravity also compressed it, which also heated it up more. When it was hot enough, the silicate minerals and metals melted. Because the metal is denser, it sank, becoming the Earth’s core, and the silicate minerals rose to become the mantle.
habitable zone
The zone where liquid water and, potentially , life exist.
Kepler Mission
Measures the brightness of stars and looks for variations in the brightness. 1,030 confirmed planets. Hoping to find earth-like planets and estimate how many are in our galaxy. Found billions of Earth-sized planets in the Milky Way, about 5% in the habitable zone.
Transit method
measuring variations in brightness as a planet passes in front of it’s sun. By seeing which wavelengths of light pass and which are absorbed we can extrapolate what the planet is made up of
TESS mission
- survey the brightest stars near Earth for exoplanets. 440 confirmed, 7,130 candidates – likely 80% ish will be confirmed planets.
James Webb Space Telescope
Looking for biosignatures or signs that life exists
biosignature
Biosignatures include:
o Oxygen - photosynthesis
o Ozone - lots of oxygen over time
o things that can’t be made abiotically
o Carbon dioxide – animal breathing
o Methane – bacteria and animal farts
o Dimethyl sulfide – phytoplankton
Kuiper belt and Oort Cloud
Contain bodies primarily composed of ice as well as rocky fragments and dust
Fost line/snow line
Dividing line between planets close to the sun, where it is too hot for anything but silicate, minerals, and metal to crystalize, and the outer part of the disk, where it is cool enough for ice to form.
