The solar system pt 2

The solar system

pt 2MR. BANKS

8TH GRADE SCIENCE

Dwarf planets

Following the discovery of multiple objects similar to Pluto

(and one that was even bigger than Pluto) a new

classification for planets was created.

1. The object must be in orbit around the Sun.

2. The object must be massive enough to be a sphere by its

own gravitational force.

3. It must have cleared the neighborhood around its orbit.

There can’t be any other large objects near the path the

“planet” orbits in.

Dwarf planets

There are currently five

confirmed dwarf planets

Pluto, Ceres, Haumea,

Makemake, and Eris

There are an estimated

200 dwarf planets in the

area “near” Pluto, and as

many as 10,000 dwarf

planets orbiting the sun at

extreme distances.

Pluto

The first dwarf planet discovered.

Pluto is small, about 2/3 the size of

our moon.

We know little about Pluto, it is

likely rocky and very cold.

It has five moons – the largest,

Charon is about 1/10 the size of

Pluto itself.

Pluto

Pluto has a very odd orbit

compared to the other

planets, another reason it

didn’t make sense to

include it as a planet.

New horizons

A space probe launched in

2006 on a mission to

investigate Pluto.

It has also investigated an

asteroid and Jupiter on

the way.

The dwarf planets

Eris – The largest dwarf

planet, ¼ the size of Earth.

Takes 558 years to orbit the

sun.

Haumea – Has two moons,

observations of telescope

images suggest that

Haumea is an ellipsoid.

Makemake – Not much is

known about it besides that

it is about 2/3 the size of

Pluto.

Ceres The largest object in the

asteroid belt between Mars

and Jupiter.

There are a pair of bright

spots located in a crater,

it’s not clear what they are.

It accounts for 1/3 of the

total mass of the asteroid

belt.

Ceres has a thin dusty outer

layer over a layer of water

ice with a rocky core.

The Dawn space probe

entered into orbit on April

24th and should help gather

more info on Ceres.

Comets

A small object orbiting the sun

in an elliptical orbit.

When it passes close to the sun,

the comet heats up and the

materials that make up the

comet begin to escape out into

space.

The materials are blown away

in the solar wind and from a

stream of visible particles

known as the tail of the comet.

This can include water, carbon

dioxide, methane, ammonia or

even rock dust.

Rosetta

Launched in 2004.

Investigated several asteroids

before achieving successful

orbit around the comet 67P.

Asteroids

Also known as minor planets or planetoids.

Defined as anything above a certain size that isn’t

rounded like a planet and isn’t a comet.

Can range in size from 1,000 km to 10 m.

Generally composed of rock and ice.

Meteors

A small rocky or metallic

object traveling through

space.

They range in size from a

grain of sand to 10 meters

wide.

Most are fragments that

have broken off comets or

asteroids.

Meteors that enter Earth’s

atmosphere are the

“shooting stars” seen at

night.

Meteors

As they fall through the

atmosphere, friction from air

molecules heat the surface of

the meteor and melt/break it

apart.

What lands is only a small

fraction of the original object.

In space they are known as

meteoroids.

When falling through the

atmosphere they are meteors.

And on Earth they are

meteorites.

The asteroid belt A region of space roughly

between Jupiter and Mars

that is occupied by

millions of asteroids.

We’ve identified

hundreds of thousands.

Over 200 are greater

than100 km wide.

Collisions between

asteroids happen

frequently (on an

astronomical time scale)

with large asteroids

colliding about every 10

million years.

The Kuiper belt

Similar to the asteroid belt in that it contains large numbers of “small” objects.

However it is far wider and there are much more massive objects located there.

All the known dwarf planets besides Ceres are located there.

It extends from the orbit of Neptune outward another 1,800,000,000 miles.

The Oort cloud

A theoretical sphere of icy bodies that extends out far away from the Sun, as far as 2 light years.

Studies of comets and their orbits have given rise to the hypothetical existence of this region.

The Oort cloud comprises the theoretical extent of the gravitational influence of the sun.

None of our current probes will reach what is thought the be the outer edge of the cloud before their batteries run out.