EARTH
Did you know that Earth is the only planet in our solar system that is known to have life on it? Can you
imagine a world without trees, animals, or even people?
We can live on Earth because we have air and water- two things that most planets do not have. Weird,
huh? All of the things that we need to survive are able to exist because our thin atmosphere separates us
from outer space. Earth also has a moderate average temperature that is good for living things (59
degrees Farenheit). Remember how hot Venus is? Imagine how hot Venus must get!
Earth is on the terrestrial planets (the others are Mercury, Venus, and Mars). This means that the surface
of Earth has changed a lot over time because of volcanic action, movements of Earth crust and because
we’ve been hit by other objects from space. Even today, the Earth is still changing. In a million years
Earth might be very different than it is today.
Earth is the third planet from the sun and fifth largest planet in our solar system.
MENTION ROTATION AND REVOLUTION (DAY V. YEAR)
MOON
We have four different seasons because the Earth’s axis of rotation is tilted more than 23 degrees. To
learn more about the seasons and why we have them, click here!
MARS- the fourth planet from the sun!
Have you ever heard of the Red Planet? That’s Mars! Did you know that it takes Mars the same
amount of time to revolve around the sun as it takes Earth? Can you figure out long one
revolution around the sun takes?
Another similarity because Mars and Earth is that they are both terrestrial planets. Remember:
that means that Mars’ surface changes over time.
Other than that, however, Mars is very different from our planet. The atmosphere on Mars (GET
AVG TEMP) is very cold and very dry. Sometimes there are huge dust storms that take over the
entire planet! These storms can really affect the planet: they can create enormous dunes, wind
streaks, and even change the surface of the planet!
MOONS????
TEMPERATURE
Could you live here? Why or why not?
JUPITER
Jupiter is by far the biggest planet in our solar system. In fact, if it had been 80 times bigger it
would have been a star!!
Jupiter is mostly made of hydrogen and helium. There is no oxygen.
Jupiter has four huge moons. They are so big that an astronomer named Galileo was able to see
them with a very old weak telescope way back in 1610. We call the moons the Galilean
satellites, in honor of Galileo. The moons are so big that they are actually the size of other
planets in our solar system! Jupiter has other moons besides the Galilean satellites. All together,
Jupiter has 63 moons. That is a LOT!!! Think about it: how many do we have on Earth?
Astronomers have discovered a lot about Jupiter’s moons in the past 400 years. Io, one of the
Galilean satellites, for example, has the most active volcanoes in the entire solar system! The
moon Ganymede is the biggest moon in our solar system and is the only moon that has its own
magnetic field.
Jupiter is often hit by meteorites and asteroids. Some astronomers think that some of Jupiter’s
moons might actually be asteroids that have been pulled in by Jupiter’s gravity.
WEATHER
ATMOSPHERE
Could you live here? Why or why not?
SATURN
Saturn is famous for its rings. They are called the A and B rings. They were discovered by
Galileo in 1610. Galileo also discovered the moons of another planet with the exact same
telescope! Do you remember which planet it was?
Saturn’s atmosphere is a lot like Jupiter’s. It is mostly made up of hydrogen and helium. Do you
think there is oxygen?
It is much bigger than Earth – in fact, Saturn’s volume is over 700 times bigger than Earth’s!
Parts of Jupiter can get very windy. Sometimes, the wind reaches 500 meters per second. That is
MUCH faster than a hurricane. (The strongest hurricane-force winds recorded on Earth reached
about 100 meters per second. Can you imagine how fast the wind must blow on Jupiter? We
wouldn’t even be able to stand!)
TEMPERATURES
Could you live here??
NEPTUNE- the eighth planet from the sun
Neptune was the very first planet that was located because of mathematical predictions rather than
observation. Guess who predicted it? (Here’s a hint: he discovered Jupiter’s moons and Saturn’s rings.)
Neptune is about 2.8 billion miles away from the Sun. That is a long way! Think about far away the sun
seems from our planet. Do you remember how far away Earth is from the Sun? How much further is
Neptune? Because Neptune is so far away from the Sun, it gets very, very cold here.
We can’t see Neptune without a telescope because it is too far away from Earth!
It takes Neptune 165 Earth years to orbit around the Sun just once. Do you remember how many years it
take Earth?
Neptune is the eighth planet from the Sun, but sometimes it is actually the ninth! Because Pluto has an
elliptical orbit, (If you have any questions about what ellipses are, click here!)
TEMPERATURE
ATMOSPHERE
WEATHER
Could you live here??
PLUTO
Pluto is the smallest, coldest, and farthest planet from the Sun in our solar system. Some scientists,
however, think that Pluto might also be part of another type of solar system that orbits around something
called the Kuiper Belt. The Kuiper Belt has thousands and thousands of tiny icy worlds; many
astronomers think that these ice planets might be the source of comets.
Because Pluto is very aware from the Sun, it completely freezing here…MUCH colder than it gets on
Earh. The average temperature on Pluto is only THIS TEMPERATURE. Think about the average
temperature on Earth. That is a huge difference!!
Pluto moves in an elliptical orbit. (Click here to learn more about ellipses!) Because of the elliptical shape
of Pluto’s orbit, Pluto is actually closer to the Sun than the eighth planet Neptune for 20 years every 248
Earth years. The last time Pluto was closer to Earth than Neptune was 1979. When will this happen
again?
No spacecraft has ever traveled to Pluto. This January, however, NASA sent the New Horizons to explore
Pluto and the Kuiper Belt. THEY WON”T BE BACK FOR THIS LONG. As a result, most of what we know
about Pluto are from observation. The New Horizons missions will answer a lot of the questions we have
about Pluto!
TEMPERATURE
ATMOSPHERE
WEATHER
Could you live here??