THE SOLAR SYSTEM…

Colella Lavinia classe 3 ^ sez A

THE PLANETS…

THE INNER PLANETS…

MERCURY

MARS

VENUS

EARTH

The four innermost planets in the Solar System are

sometimes called the "terrestrial" planets because of their

proximity to the Earth and their similarity as compact solid

bodies with rocky surfaces. These four planets developed

from small grains of dust that collided and stuck together

to form pebbles, boulders, kilometer- and mile-sized

planetesimals, and larger planetary embryos and

protoplanets). They formed in the inner portion of the

protoplanetary disk located closer to the developing Sun.

During the first 100 million years of the System's birth it

was too warm for the four developing protoplanets to

agglomerate water and more volatile ices and bulk up

sufficiently in gravitational might to hold onto the abundant

but lightest gases of the Solar nebulae to become ”gas

giants."

THE OUTER PLANETS…

• The outer planets are also called the Jovian planets or gas giants. Like

the inner planets, the outer planets have similar characteristics to one

another.

• The outer planets are so much larger than the inner planets that they

make up 99 percent of the mass of the celestial bodies that orbit the

Sun. Although mainly composed of gas, the outer planets also have

other ingredients. Somewhere at the center is what scientist refer to as

a rocky core, although it is actually composed of liquid heavy metals.

While the inner planets have few or no moons, the outer planets have

dozens each. The inner and outer planets are separated by the

asteroid belt.

URANUS

JUPITER

NEPTUNE SATURN

STARS…

A star is a celestial body that shines with its own light. Inastronomy and astrophysics the term indicates a luminousspheroid of plasma that generates energy in its own nucleusthrough nuclear fusion processes. This energy is radiated intospace in the form of electromagnetic radiation, flow ofelementary particles (stellar wind) and neutrinos. A good partof the chemical elements heavier than hydrogen and helium(the most abundant in the universe) are synthesized in thenuclei of the stars through the process of nucleosynthesis. Thestar closest to Earth is the Sun, the source of much of ourplanet's energy. The other stars, with the exception of somesupernovae, are visible only at night as bright spots, whichappear flickering due to the distortion effects caused by theEarth's atmosphere.

THE SUN…

The Sun is the star at the center of the Solar

System. It is a nearly perfect sphere of hot plasma,

with internal convective motion that generates a

magnetic field via a dynamo process. It is by far the

most important source of energy for life on Earth.

People think that the Sun is the biggest star of all,

but is actually quite small. Some of the big stars,

such as Arcturus, are hundreds of times bigger than

the Sun. Arcturus looks much smaller than our Sun

because it is so far away. The stars shine all the

time, but we can see them when the Sun is low in

the sky or at night. This is because the light from the

Sun is so bright that we cannot see other stars

shining.

RANDOM SCIENCE

FACTS AND TRIVIA…

WHAT MAKES DAY AND NIGHT?

The Earth moves in two differents ways. It rotates on its axsis, and it also revolves around the Sun (this iscalled its orbit). It takes the Earth approximately twenty-four hours to rotate on its axis. This creates dayand night, because the parts of the Earth that are far from the Sun will be in total darkness. The Sundoesn’t move , but because we cannot feel the rotation of the Earth, we feel that the Sun is moving, notus. The sun appears to come up every day in the East and go down at the end of the day in the West.

WHAT MAKES THE SEASONS?

It takes the Earth approximately 365 days to go round the Sun. It travels around the Sun in anticlockwisedirection. The Earth is tilted on its axis. As it travels around the Sun, sometimes the northen half of the planet ( the northen hemisphere) is nearer to the Sun, and sometimes the southern half (the southernhemisphere) is nearer. This creates the seasons. If you are on the part of the Earth that is near the Sun, it issummer, with lots of daylight. If you are on the part of the Earth that is far from the Sun, it is winter, with more darkness. This explains why days are longer in summer and shorter in winter. If you are in one of the polar regions, it may be daylight or darkness for 24 hours.