Astronomy Notes

1. Astronomy is: Science that deals with celestial objects, space, and the physical universe

2. The Universe consists of: All of space and the matter it contains 3. Galaxies are: Large grouping of stars in space

4. Describe and draw 3 categories of Galaxies : Spiral (disc) shaped galaxies they have a bulge in the center and distinct spiral shaped arms.

2. Elliptical galaxies – have a spherical or elongated shape

3. Irregular galaxies – have no distinct shape

5. The earth is located in which category of galaxy? Spiral/Disc shaped What is the name of our galaxy? The Milky Way galaxy

Huge objects in space that give off light and heat 6.Stars are: Huge objects in space that give off light and heat They are born in a large cloud of gas and dust Called the Nebula AKA Hollywood of the Solar system

7. There are many stars in the Milky way Galaxy 7. There are many stars in the Milky way Galaxy. Our sun is a medium sized star. It is located in an outer arm of the galaxy and is the source of all Life on earth. The sun’s mass makes up over 99% of the mass of the entire solar system

8. Light and heat from stars come from nuclear reactions within the star. The main gasses that make up stars are Hydrogen and helium. Young stars are rich in Hydrogen, while older stars are rich in Helium.

9. The Hertzsprung-Russel Diagram ( H-R diagram) shows: The relationship between a stars temperature and its Luminosity. 10. The Astronomers use the H-R diagram to: Classify stars according to their color, temperature, luminosity, spectra type, and evolutionary stage.

H-R diagram

H-R diagram

H-R diagram

11. Stars are measured by their Temperature which is shown on the X axis of the H-R Diagram and their brightness or luminosity which is measured on the Y axis of the H-R diagram. Most stars spend their lifespan on the Main Sequence of the H-R diagram.

The coolest stars are : orange or red 12. The amount of energy produced by a star determines its surface temperature and color. Hot stars are : blue or white The coolest stars are : orange or red

Life Cycle of a Star

Natural satellites of a planet 13. Moon’s are: Natural satellites of a planet 14. Comets are: Bodies of ice and rock and dust that orbit the sun

A small rocky body that revolves around the sun 15. Asteroids are : A small rocky body that revolves around the sun

16. Meteoroid's are (in space) : Rocky bodies (smaller than an asteroid) that orbit the sun Meteors are (in the atmosphere): A meteoroid that burns and vaporizes “shooting stars” Meteorites are (on the ground) : A meteor that survives the atmosphere and lands on the earth. ( 90% Iron)

It takes 8.3 minutes for light to travel from the sun. 17. A Light year is a unit of length ( not time) in Astronomy that is equal to the Distance light travels in one year in a vacuum. ( approximately 5.88 trillion miles or 9.46 trillion Kilometers. It takes one year for light to travel one light year It takes 8.3 minutes for light to travel from the sun. It is 8.3 light minutes away.

Objects in space that are in redshift are moving away from earth 18. Wavelengths travel through th4e earth’s atmosphere with varying frequencies. Objects in space that are in redshift are moving away from earth Objects in space that are in blueshift are moving toward earth(blue to you)

Draw a picture of the Milky way galaxy Draw a picture of the Milky way galaxy. Place a dot in one of the outer arms to represent our solar system