9th Grade Earth Science - Astronomy

Nebula

A cool cloud of gas (mostly Hydrogen) and dust.

Protostar

A baby star that is too cool to start nuclear fusion.

Main sequence star

A star in which forces caused by gravity and nuclear fusion in the core are in balance. Most stars are this kind of star.

Red giant

A star that has expanded its outer layer due to using all of its Hydrogen fuel. Fusion of Helium into Carbon starts. Happens in the life spans of medium sized-stars.

Supergiant

A very large red giant. Happens in the life spans of very massive stars.

White dwarf

A white star about the size of earth. Happens to small and medium sized stars near the end of their lifespans.

Black dwarf

A white dwarf which has cooled and become dim.

Supernova

An explosion caused by gravity collapsing a supergiant when it runs out of nuclear fuel.

Neutron star

A very dense, hot star about the size of a city, a remnant of a massive star.

Black hole

An infinitely small, dense object, which not even light can escape. The fate of some extremely massive stars.

Visible light

The small portion of wavelengths that are visible to us as color.

Blue stars

The hottest of main-sequence stars, that burn out the fastest due to being hot and massive.

Red stars

The most numerous of main-sequence stars, that have very long life spans due to being small. Live about 100 billion years; so none have died yet in the universe.

Bing bang theory

The theory explaining how the universe began as a very dense mass, then exploded outwards, forming into stars and galaxies.

Hydrogen to Helium

The kind of nuclear fusion that occurs in a main-sequence star

Helium to Carbon

The kind of nuclear fusion that happens in a red giant

Carbon to Magnesium → Magnesium to Iron

Kinds of nuclear fusion that occur in a supergiant star

Color and brightness

Two things that indicate the temperature of a star.

(angular size)/360 = (actual size)/2pi*distance

Proportion showing relationship between angular size, actual size, and distance of an object, used to determine these things about an object in space.

Max wavelength = (2.9×10²)/Temp (K°)

Wein’s law, used to find temperature of stars based on their spectographs.

UV

Hotter objects emit more energy and light near the ___ end of the spectrum.

infrared

Cooler objects emit more energy and light near the ______ end of the spectrum.

300,000km/sec

Speed of light

13.7 billion years

Age of the universe

4.6 billion years

Age of the Earth

State the problem (ask a question about something)

First step of the scientific method

Gather info (based on experience observations or research)

2nd step of the scientific method

Form hypothesis

3rd step of the scientific method

Test hypothesis (perform experiment, collect data)

4th step of the scientific method

Analyze results (graph/chart your results)

5th step of the scientific method

Conclusion (do your results support or refute your hypothesis?)

6th step of the scientific method

Scientific theory

An explanation of a phenomena which has evidence to support it and is widely accepted.

Scientific law

A claim proven without exception. Usually a mathematical formula (e.g. Wein’s law)

Hypothesis

An unproved explanation for a phenomena. Must be tested thoroughly before it becomes a theory.

Observation

Something that you perceive (objective) (e.g. it is snowing)

Inference

An assumption you make based on observations (e.g. it is snowing so it must be below freezing)

Prediction

An idea of something that is going to happen in the future, based on evidence. (like a weather forecast)

Astronomy

A branch of earth science that studies space, the stars, and the universe as a whole.

Meteorology

A branch of earth science that studies the atmosphere, including the weather and climate.

Oceanography

A branch of earth science that studies physical properties of the ocean, such as currents and erosion.

Geology

A branch of earth science that studies the Earth’s physical structure and substance, its history, and processes that act on it, such as rock layers and plate tectonics.

Blue-shift

When objects are moving towards you, sound or light waves being emitted from them are shifted towards the high end of the spectrum. With sound, the pitch is higher, with light, it appears bluer.

Red-shift

When objects are moving away from you, sound or light waves being emitted from them are shifted towards the low end of the spectrum. With sound, the pitch is lower, with light, it appears redder.

Cosmic background radiation

Microwaves left over from the big bang which are spread fairly evenly throughout the universe.

Stellar parallax

A method of determining a star’s distance from the observer. A star is observed against more distant stars from 2 different locations, and its location relative to these stars is marked. Draw a line from the observing positions to the apparent location of the star from each of these positions, where they intersect is the true distance the of the star.

red-shifted

Distant galaxies’ spectra appear ______ because they are moving away from Earth.

Bright-line (emission) spectrum

A spectrum which is mostly dark aside from bright lines of color. Emitted by hot, low-pressure gas.

Dark-line (absorption) spectrum

A spectrum which appears as a solid rainbow except for periodic dark lines. Caused when cool gasses or are between a continuous spectrum and the observer, causing certain wavelengths of light to be absorbed, depending on the kind of atoms. Can also be when a filter is between the light source and the observer. This kind of spectrum is emitted by stars.

Continuous spectrum

A spectrum which appears as a solid rainbow of color. Emitted by, for example, an incandescent lightbulb.

Doppler effect

Waves of sound/radiation emitted from moving objects are squished/stretched depending on if they are moving towards or away from the observer.