1. Order of the Planets from the Sun
Acronym- My Very Educated Mother Just Served Us Nachos.
Planets- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

2. Requirements to be Called a Planet!
Round
Revolve around the sun
Orbit the sun in the same plane/position as the other planets.

3. Mercury The closest planet to the sun
Has the shortest revolution- 88 days
The smallest planet
No moon

4. Venus
The hottest planet because it is so close to the sun and has a thick atmosphere to hold in energy- greenhouse effect
Visited by the Russian probe Venera
Covered in Volcanoes

5. Earth
The living planet; the only planet we know that has life

6. Mars
Most similar to earth (in diameter, mass, rotation and revolution, temperature)
Has 2 moons
Has some water in the frozen ice caps at its north and south poles

7. What separates Inner planets (Terrestrial) from the outer planets (Jovian)
Asteroid belt just beyond Mars, separates inner planets from outer planets.

8. Jupiter The largest planet Has at least 17 moons and 4 rings
Has the Great Red Spot: A calm area surrounded by a stormy atmosphere
Europa may have ocean beneath ice surface.

9. Saturn
The least dense planet- could float on water because it is less dense than water
24 moons
Rings made of chunks of ice
Has a huge system of rings around it made of billions of chunks of ice & rock

10. Uranus Obits the sun on its side 20 moons
Appears turquoise due to methane gas

11. Neptune The farthest planet from the sun The coldest planet
Has 8 moons and 4 rings
Has the longest revolution
Has Great Dark Spot (a massive storm)- has vanished.

12. Planet Mini-Quiz! Which planet is the most similar to earth?
Which planet is made mostly of methane gas?
Which planet can float on water?
Which planet is the hottest and why?

13. Solar System Debris

14. Comets & TNOs
Comets- Dust particles in a mixture of H2O, CO2, Methane, & Ammonia. “dirty snowballs”
Comets found in Edgeworth-Kuiper Belt beyond Neptune as solid body called nucleus.
When a comet travels in orbit close to sun (near Jupiter), it heats & solar wind forms a Coma (tail-gas & dust).
Coma trails behind comet until it moves away from the sun, then the tail is in front of the comet.

15. Comets Halley’s Comet has a orbital period of 76 years.
Last visible from Earth in 1986
Named from Edmund Halley,18 century English astronomer-accurately predicted it’s arrival by looking at when previous comets had appeared.

16. Continued.. TNOs- Trans Neptunian Objects.
Large bodies up to several hundred kilometers.
Located in the Edgeworth-Kuiper Belt.

17. Asteroids Solid, rock-like masses. Irregular shape.
Believed to be leftover material from solar system formation.
Revolve around sun, most in circular orbit in asteroid belt.
Some have long elliptical orbits.

18. Continued… Perihelion- closest to sun
Theory: an asteroid or comet collided with Earth, causing dinosaur extinction 65 mya.
Scientists are currently researching ways to prevent collisions with Earth by diverting objects before they reach Earth.

19. Asteroid pics

20. Meteors & Meteoroids
Meteoroid- rock or icy fragment traveling in space. Range of sizes.
Meteor- light made by a meteoroid passing through Earth’s atmosphere. (shooting star)
Meteor Shower- when Earth passes through a comet’s tail & many particles from tail burn up in Earth’s atmosphere as meteors.

21. Meteor shower

22. Meteorites
The part of a meteoroid that survives to strike Earth’s surface.
3 Types:
Stony (94%)
iron (5%)
stony-iron (1%)
Most abundant meteorites in Antarctic ice cap because they are exposed et the surface when wind erodes the ice around them.

23. Impact Craters
Bowl-shaped depressions made by meteor/object that strikes a surface.
About 150 known impact craters on Earth
Arizona’s Barringer Meteor Crater.
Earth is geologically active & erases the marks of impacts. Oldest Earth crater- Vredefort Crater in South Africa 2 byo.

25. What happens to comets as they approach the sun?
Assignment: Write down & answer the following questions on a separate sheet of paper.
What happens to comets as they approach the sun?
Where are most asteroids found?
Explain the difference between meteoroid, meteor, & meteorite.
Most meteorites formed between 4.55 & 4.65 b.y.a., making them a little older than the oldest moon rocks. Infer why moon rocks are younger than most meteorites.