The Inner Planets SPI 0507.61 & SPI 0507.62

Learning Target I can distinguish the planets by their appearance and location to the Sun. I can draw conclusions about planets using graphs.

On which planet would a person weigh about as much as he or she weighs on Earth?

Approximate Radius at the Equator (km) According to the table, about how many times greater is the radius of the largest planet than the radius of the smallest planet? Planet Approximate Radius at the Equator (km) Mercury 2,440 Venus 6,052 Earth 6,378 Mars 3,397 Jupiter 71, 492 Saturn 60, 262 Uranus 25, 559 Neptune 24, 476 10 times greater 30 times greater 100 times greater 300 times greater

How much do we know about the planets in our solar system?

Words I Need to Know… Revolve/Revolution: one complete trip around the sun Rotation: a complete spin on an axis

What are planets? Solar System- Made up of a star and the objects that orbit around it. Planet- A large object that orbits a star.

What are planets? Inner planets- The planets that are closest to the Sun. (name the inner planets) ___________, ____________,___________, & ___________. We also know these planets as terrestrial planets because they have surfaces made of rock.

What are planets? The outer planets have surfaces made of gases. (We will learn more about these planets next week.)

Which two planets lack a moon? Moon- a natural object that orbits a planet. All but two planets in our solar system have one or more moons. Make a prediction. Which two planets lack a moon?

Why wouldn’t they have moons? Scientists are not entirely sure why Mercury and Venus lack moons altogether. According to one theory, as the two innermost planets in the solar system, they are close enough to the sun that the sun's gravity overwhelms their own gravitational pull. Any satellite that formed around Mercury or Venus during the origin of the solar system (or any asteroids captured later on) would eventually be tugged away from those planets by the sun's much stronger gravity.

Asteroids- A rock that revolves around the Sun Asteroids- A rock that revolves around the Sun. There are thousands of asteroids in our solar system. Most asteroids are located between Mars and Jupiter in the asteroid belt.

How do the surfaces of the inner & outer planets differ? Which type of symbiotic relationship occurs when one organism benefits while the other is neither helped nor harmed?

Other than planets, what other objects are in a solar system? Which type of organism returns nutrients to the soil?

How does Mercury, Venus, and Mars compare to Earth?

Mercury The closest planet to the Sun 1/3 the size of Earth The average temperature of Mercury’s surface is 1790C. No rings Surface is scarred with craters Rotates on its axis every 59 “Earth” days No true atmosphere, so the temperatures are extremely low at night

Scientific Calculations If Mercury rotates on its axis every 59 “Earth” days, how many hours are in one day on Mercury? If it takes Mercury 88 “Earth” days to make one revolution, how much greater is Earth’s revolution?

Venus Second planet from the Sun It is almost the same size as Earth Surface is covered with vast plains, volcanoes, huge mountains, and craters The atmosphere has a thick layer of clouds and carbon dioxide Surface temperatures are around 4800C, so it is the hottest planet Venus and Mercury are the only planets that do not have a moon orbiting them.

Venus Venus rotates in the opposite direction from Earth. It rotates once every 243 “Earth” days. It revolves around the Sun in 225 “Earth” days. Compare the amount of time in one “Venus” day to one “Venus” year.

Earth The third planet from the Sun Earth’s rotation = __________ hours Earth’s revolution = __________ days The only planet known to support life

Earth The largest inner planet It contains 21 % of oxygen in its atmosphere. What causes Earth’s atmosphere be so much different than its neighbors? (contains oxygen)

What direction does the Sun rise and set on Earth?

Recall that Venus rotates in the opposite direction of Earth. If you were on Venus, what direction would you see the Sun rise and set? Recall that Venus rotates in the opposite direction of Earth.

Mars The fourth planet from the Sun It has a rotation period of 24.6 hours. (Whose rotation does that remind you of?) Mars has no seasons. The skies appear to be pink because of the reddish dust in the atmosphere. Ice caps have been found to have frozen carbon dioxide and water at the Martian poles.

Exit Ticket On a post-it note, answer the following questions using the charts in your book. 1.) Which planet has the warmest surface temperature? (page 155) 2.) How does the size of Mercury’s core compare to Earth’s core? (page 157) 3.) A year on Mercury is a. shorter than a year on Venus b. longer than a year on Earth c. the same as a year on Earth d. the same as a year on Mars