:: Black holes

What are black holes?

A black hole is a hole that is black because it absorbs everything, including light. Every time it absorbs something, the black hole gets larger and fatter.

Where can we find black holes?

We can find black holes in the center of Galaxies.

Can we get out of a black hole?

No light can get out. Millions of years after the creation of the black hole, the black hole gets smaller and smaller untill there is nothing left and things may be able to get out.

:: Supernovae

Supernovae are the result of an explosion of a very big star which is finishing its life.

Supernovae are almost 8 times bigger than the sun. At some point, the supernova shines more than a galaxy and has more energy than 200 million stars like the sun!!!In the center of the supernova a star remains : it is called a pulsar.

Image via Wikipedia

:: Atlantis est revenue / came back !

Les astronautes partis réparer le télescope Hubble sont revenus. Leur navette Atlantis avait un parachute pour ralentir...

The astonauts who went for the reparation of Hubble came back. They needed a parachute to slow down at the end...

:: Neptune

Neptune is the 8 th planet from the Sun and the 4 th largest planet.

Neptune has a storm that is called the great dark spot. Like Uranus it is blue because of its gazes.

Scientists think that there is a very large ocean under Neptune's clouds.

Neptune a is bit smaller than Uranus but is heavier.

Neptune has only been visited by Voyager 2.

• Distance to the sun: 4,498,252,900 kms.
• Diameter: 49,528 kms.
• Duration of rotation: 16.11 days.
• Duration of revolution: 60 181 .3 days.

:: Stars

Stars
Some of them are big blue ones, big red ones, yellow ones and red ones. Big blue ones are the hottest ones.
Red ones are stars at the end of their lives and they are the coldest ones.
Yellow stars are like our Sun (which is a yellow star!).
Red ones are the best known ones.
In countries that do not have too much polution we can sometimes see more than 3000 stars all over the sky.
The big ones are 100 to 200 times larger than the Sun. Stars are composed of gaz and fire.

:: Galaxies

There are more than billions of Galaxies in the universe.There are three kinds: Elliptic, Irregular and Spiral. Galaxies move around and crash into each other, our Galaxy also does that. When Galaxies crash, their stars don't get mixed up, they stay in their own galaxies.

Galaxies are a billion times shinier than the sun and once a man invented glasses so we could look at them.

• This is a spiral Galaxy in black and white (some look a bit different). Our Galaxy is a spiral one.

• These are some pictures of Irregular Galaxies.

Irregular Gallexies are normally in any shape and in any colour. Irregular Galaxies are my favourite ones.

• This is a picture of an elliptic galaxy. Around there are other galaxies.

:: Mars 2 moons: deimos and Phobos

Mars has two moons : Phobos and Deimos.

Phobos:

Diameter: 10 kms

Distance to Mars: 9000 kms

It is composed of different kinds of rocks.

It looks like an asteroid.

Deimos:

Dimensions (it is not round): 10 x 12 x 15 kms.

:: Mars

It is located just after the Earth and it is the seventh largest planet.

It is red because its desertic surface made of rocks, has a reddish colour, due to the clouds of iron dioxide raised by strong winds.

For the Romans, Mars was the God of war.

Mars is visible at night without a telescope.

The first satellite to visit Mars was Mariner 4; it was followed by others.

The largest volcano in the solar system is situated on Mars, it is called Olympus Mons. The Diameter of Olympus is 648 km and its height is 22.5 kilometers.

Scientists are still trying to discover if there was life on Mars a long time ago, a proof that there could be is that astronomers are sure that there has been water on mars. NASA's Phoenix mars lander discovered water ice on mars the fourth august 2007.

• Distance to the sun: 228 million kms.
• Diameter: 6794 kms.
• Duration of revolution: 687 days.
• Duration of rotation: 1 days and 37 minutes.
• Temperature: -133 °c to 27°c!!!

:: Good Bye Hubble !

:: Uranus moons

Uranus has 21 named moons and 6 unnamed ones.


Small moons:
Juliet
Portia
Rosalind
Belinda

Puck

Cordelia

Bianca

Cressida

Desdemona

5 main moons of saturn:

Oberon

Titania

Umbriel

Ariel

Miranda

They are composed of ice and rock. There are more moons.

:: Uranus rings

Uranus has 13 rings that are kind of dark and are made of rock and dust. They are hard to observe.

:: La réparation du satellite Hubble !:Reparation of hubble!

Hubble has a problem so we sent some people to reparate it.

Hubble a un problem alors on a envoyer des gens pour le reparer.

Si vous voulez voir les plus belles images de l'opération, cliquez ici.
If you want to see some pictures, clic here.

:: Uranus

Uranus is the third Gaz Gigantic Planet And seventh from the sun.

Uranus is containd of: rock, different kind of ice, 15° helium, 83° hydrogene and 2° methane. It gaz gives its blue light.

• Diameter: 51 100 kms.
• Distance to the sun: 2,9 milliards of kms.
  
• Duration of rotation: 17 hours.Uranus looks like it is on its side and it turns in that orbit.
  
• Duration of revolution: 84 hours.

:: Jupiter

Jupiter is the fifth planet and the largest one in the solar system.

There is a ring system, but it is very faint and is totally invisible from the Earth.

Jupiter is the third shiniest after the sun!

Jupiter has been visited for the first time by the satellite Pioneer 10.

Jupiter has a great red spot (which is a storm), that has been observed 300 years ago.

The spot is big as 3 times the Earth!

The comet Shoemaker-levy 9 crashed into Jupiter. What we could see was incredible!

Jupiter is composed of gases caled hydrogen and helium, and other gases over a tiny rocky core.

Most other planets in other solar systems are a bit heavier than Jupiter but Jupiter is larger than them.

• Duration of rotation : 10 hours!
• Duration of revolution : 12 years!
  
• Diameter : 142,981 kms. 11 times the Earth!
  
• Distance from the sun: 779 million kms.
  

:: Venus

Venus is the second planet from the sun, and the seventh largest. It is Earth's neighbour and has been observed by satellites.We sometime call Venus the Evening star because at night (a long time ago) people thought it was a star and it was the first to shine. Now we know Venus is not a star but a planet.

Quick facts

• Moons: none
• Distance from the sun: 108 200 000 kms.
• Diameter: 12104 kms.
• Duration of revolution: 224,7 days.
• Duration of rotation: 243 days.

Venus's rotation is so slow that a Venus year is smaller than a Venus day.

At some point, astronomers thought Venus was divided in 2.

Surface

About 85% of Venus's surface is covered by volcanic plains covered by layers of lava. There are a lot of craters on Venus but still very few compared to Mercury and the Moon.

Spacecrafts

The first spacecraft to observe Venus was Mariner 2. Since then other spacecrafts have orbited Venus. A few landed on the planet's surface, were able to send a few pictures back to Earth and melted.

Orbit

Venus's orbit is the one that is the less elliptical. It is the only planet to turn in a different direction.

Atmosphere

Venus's atmosphere is composed of: 90.5 % carbon dioxide, 3.5% nitrogen and other gases.

Venus's clouds contain a little water vapor, but we have little reason to think that water in any form exists on the planet itself. We think that most of the water that initially existed on Venus evaporated, when the Sun started to get warmer, and moved up to the upper atmosphere. This created a greengas effect, making the planet even warmer.

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:: Jupiters : 63 moons !

Jupiter with its 63 moons.

Names coming from Zeus's servants etc...

Let me present the four mane ones, discovered by Galileo in 1610...

Europa

The latest discoveries show that there may be life on Europa, the ice field that covers Europa seem to hide a ocean, very exiting indeed but the possibilities of life are small.

Europa is smaller than The Moon but much brighter, in fact it's one of the brightest moons in the solar system. This is caused because of sunlight reflecting off a relatively young icy crust.

Europa is named after the gorgeous Phoenician princess, who (according to the Greek mythology) was gathering flowers when Zeus spotted her and instinctively fell in love with.

• Distance from Jupiter :670 900 kms.
• Diameter: 3 138 km.
• fourth biggest satellite from Jupiter
• Discovered by: Galileo

Io

A bit bigger than the moon, Io orbits around Jupiter from about the same distance as the moon is to the earth.

Active volcanoes are present everywhere on Io.

• Distance from Jupiter: 421 600 km
• Time to orbit Jupiter: 1. 77 days
• Diameter: 3 643km
• Discovered by: Galileo

Ganymede

Ganymede is the largest moon of Jupiter, as Callisto it is mostly composed of a rocky core with a water/ice mantle and a crust of rock and ice. It was formed with 60% of rock and 40% of ice.

• Distance of Jupiter: 1. O7 million km.
• Time top orbit Jupiter: 7.15 days
• Diameter: 5262 km

Callisto

As Europa, this satellite is brighter than the moon. Callisto is a bit smaller than Mercury but contains on third of its mass.

Callisto is surely the most heavily cratered object in our known solar system. Its largest crater is named Valhalla. Valhalla's diameter is 2 485 km.

• Distance from Jupiter: 1.88 million km
• Time to orbit Jupiter: 16.69 days
• Diameter: 4821km

:: Saturn moons

Main moons of Saturn:

Prometheus

Prometheus, the third known moon of Saturn, is small and potato-shaped and it orbits Saturn in the ring F. It has a few craters of about 20 km that are in diameter visible.

In the Greek mythology, Prometheus was a titan, it is known for stealing fire from Zeus and giving it to humans.

• Distance from Saturn: 139 353 km
• Diameter: 91 km
• Time to orbit Saturn: 0.61 days

Enceladus

Tenth moon from Saturn, Encelade orbits the Planet in the Ring E. This moon is the brightest object in the known solar system. It was discovered by William Hershel in 1789. This moon displays at least 5 different types of terrain.

• Diameter: 500 km
• Distance from Saturn: 238 020 km
• Time to orbit Saturn: 1.37 Earth days

Dione

Nice and round, Dione was discovered by Cassiny the same day as Tethys. It is an icy body and is one of the densest moons of Saturn. Its surface is heavily cratered. Some of its craters are more than 100 km.

• Distance from Saturn: 377 400 km
• Diameter: 1120 km
• Time to orbit Saturn: 2.74 Earth days

Titan

Titan, the size of Mercury, is the largest of Saturn's moons. Before the Voyager encounters, scientists thought a lot of things that are now known to be wrong.

Titan's surface temperature appears to be about -178°C.

• Distance of Saturn: 1.22 million km
• Time to orbit Saturn: 15.9 earth days
• Diameter: 5 150 km

There are much more important moons of Saturn but please don't expect me to write about them because there are... 61!! Only 34 are named though.

The diameters of Saturn's moons range from 2 to 5150 kms.

:: Saturn rings

What makes Saturn so beautiful is her rings. The rings of Saturn are much more elaborate than those of any other planets.

Saturn's rings are divided into 7: D, C, B, A, F, G and E. It is hard to see the F and G rings but A, B and C are visible with a telescope.

(the F and G rings are thin)

Whene Galileo observed the rings for the first time he thought they where moons.

The rings of Saturn are about the 4,000,000 kms wide!

The distance of Saturn to the rings is like the distance of earth to the moon.

They are composed of: icy snowballs or ice covered rocks.

(This picture shows the B ring)