THE UNIVERSE

LUMINOUS AND NON LUMINOUS CELESTIAL BODIES

Luminous celestial bodiesare those that producetheir own light.

Non luminous celestialbodies are those thatdon’t produce their ownlight.

Stars are luminous

celestial bodies.

Comets, satellites

and planets are

non-luminous

celestial bodies.

NON LUMINOUS CELESTIAL BODIES

COMETS: They are ice and dust balls that movearound stars. The tail is formed when the comets getclose to the star they orbit around and they melt.

PLANETS: They move around stars. The Earth is aplanet.

SATELLITES: They move around planets. The Earth’ssatellite is the Moon.There are artificial satellites which are sent to the spaceby humans.

CONSTELLATIONS AND GALAXIES

CONSTELLATIONS: Theyimaginary lines that connect thestars that we see in the sky atnight to form shapes. Long time agothey were used to guide people’sway at night.

GALAXIES: They are groups ofmillions of stars in the Universe.There are different types ofgalaxies.

OUR SOLAR SYSTEM

Our Solar System is in the Milky Way (agalaxy).

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PLANETS MOVEMENTS

ROTATION:it is the movement by whichplanets spin on their axis. Thismovement produces days andnights.

REVOLUTION: it is themovement by which planets movearound stars. It produces years andseasons.

EARTH MOVEMENTS

ROTATION: it takes 24hours.

REVOLUTION: it takes 365days and 6 hours. Every 4 yearswe have a leap year because weadd up the 6 spare hours and weget an extra day.

4x6=24 1 day= 24hours

Solstices: • Winter: December 21st -> the longest night of

the year.• Summer: June 21st -> the longest day of the

year.

Equinoxes: 12 hours day and 12 hours night• Autumn: September 22nd

• Spring: March 20th

SEASONSThere are four different seasons in a yearbecause the Earth´s axis is tilted. As the Earthmoves around the Sun, some parts of the Earthget different amounts of light depending on themoment of the year.

SEASONSSUMMER AND WINTER

When we are in summer or in witer is because the Northern hemisphereis pointing to the Sun or pointing away from the Sun.

WHY DOES THIS HAPPEN?

WinterSummer

SEASONSSUMMER AND WINTER

The hemisphere that is pointing to the Sun getsmore heat and light than the hemisphere that ispointing away from the Sun.

Winter

Summer

SEASONSSPRING AND AUTUMN

During spring and autumn the poles aren´tpointing to the Sun. So both hemispheres getthe same amount of light. REMEMBER!!!

The Earth is always tilted. Inthis drawing we see it straightdue to the point of view.We change the point of viewto see the Earth next to theSun instead of in front of andbehind the Sun.

MOONIt is the Earth’s satellite. It orbits around the Earth.From the Earth we always see the same half of the Moon,the side that we don’t see is called the dark side.

WHY?Because the Moon takes the same time to do a complete spin on its axisand to do a complete lap around the Earth (28 days).

Imagine the Moon isa clock that goesaround anotherclock(the Earth).Every time it movesa quarter aroundthe big clock, it alsospins a quarter onitself.

MOONWe see different Moon phases.

WHY?The Moon is asatellite, a nonluminous celestialbody. We see itbecause it reflectsthe light of the Sun.

Depending on theplace the Moon is,according to theEarth and the Sun,we can see differentilluminated areas.

New Moon Full Moon

First quarter

Last quarter

ECLIPSESWHAT ARE ECLIPSES?

They are shadows produced by one non luminouscelestial body on another non luminous celestialbody.

From the Earth we can see Lunar or Solareclipses.

How are they produced?

ECLIPSESLUNAR ECLIPSES

As we said before, eclipses are shadows. A lunareclipse is the shadow of the Earth covering theMoon.

ECLIPSESSOLAR ECLIPSES

Solar eclipses are produced because the Moonproduces a shadow on the Earth. People who arein the place of the Earth where the Moonshadow is, can see the eclipse.

If you need more information or youare still having doubts, ask me by e-mail or by a comment on the blog or

in class.