STARSAND

THE SOLAR SYSTEM

In sky we can countless stars, some are bright some are not so bright.

Some of them twinkle, some are not twinkle

The object that do not twinkle are planets

Moon is the brightest object in the night sky

Moon, stars, planets and many other objects in the sky are called celestial objects

Average Distance From Earth 238,857 miles (384,403 km)

Diameter2,160 miles (3,476 km)

(about ¼ of Earth’s diameter)

Mass 1/81 of Earth’s mass

Day About 29 ½ Earth days

Temperature Day and NightDay: 261º F (127º C)

Night: -279º F (-173º C)

Gravity Multiply your weight by .17

The moon is Earth‘s only natural satellite. The moon is a cold, dry orb whose surface is studded with craters and strewn with rocks and dust.The moon has no atmosphere. Recent lunar missions indicate that there might be some frozen ice at the poles. The moon rises in the east and sets in the west

The day on which the whole disk of the moon is visible is known as the full moon day

On the fifteenth day after full moon day moon is not visible. This is new moon day

Next day only a small portion of the moon is appears on the sky, known as crescent

The various shapes of the bright part of the moon as seen during a month are called phases of the moon

Moon does not produce its own light. We see the moon when sun light falling on it get reflected towards us. So we see a part of the moon that sun light reflected towards us.

The size of the illuminated part of the moon visible from the earth increases day by day after new moon and vice versa after full moon day.

The moon completes one rotation on its axis as it completes one revolution around the earth.

The revolution of the Moon around the Earth makes the Moon appear as if it is changing shape in the sky. From Earth we see the Moon grow from a thin crescent to a full disk (or full moon) and then shrink back to a thin crescent again before vanishing for a few days.

What causes part of the Moon to be lit up?

The moon is illuminated because it reflects the light from the sun. The part of the moon facing the sun is lit up. The part facing away from the sun is in darkness.

The Moon has almost no atmosphere, because of its weak gravity. All types of gas will escape from its surface.Without an atmosphere, there is no wind or water erosion. 

The surface temperature fluctuates from roughly +300° F during the daytime to -270 F during the night. This is because there is not enough atmosphere to keep the Moon warm at night, nor protect it from the Sun's rays in the daytime.

Surface are dusty and barrenThere are many craters of different sizeLarge number of steep and high mountainsNo water in moon

On July 21, 1969 (Indian time) the American astronaut Neil Amstrong landed on the moon for the first time. Followed by Edwin Aldrin

On Space craft APOLLO 11

Definition : A celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior

The nearest star is 4.2 LY away (40 trillion km!) The distance to stars may be computed using

parallax or apparent brightnessStars appear as point sources in even the most

powerful telescopesA star’s mass may be deduced from interactions

with nearby objectsMost stars are about 71% hydrogen and 27%

helium Most stars have enough fuel to burn for

billions of years

A star’s size is estimated by mass, brightness and color

Most other useful information (including composition) is acquired through spectroscopy

Stars appear to move from east to westThat is rises in the east and sets in the westIt is due to the rotation of earthStars are gigantic gravity-induced fusion

reactorsThe core temperatures of all stars are

millions of K

The Sun is just one of 100 billion stars in our galaxy, the Milky Way.The Sun is 93 million miles (150 million kilometers) from EarthOnly about a billionth of the total energy emitted by the Sun reaches Earth.The size is about 800,000 miles (more than 1 million kilometers)across – more than 100 Earths could fit across the Sun's face. (Some stars are hundreds of times wider than the Sun!)The Sun is mostly hydrogen gas, with some helium and traces of other elements

Deep in the core*, the temperature is an amazing 27 million degrees Fahrenheit (15 million degrees Celsius)! The surface of the Sun is almost 11,000 degrees Fahrenheit (6000 degrees Celsius). The Sun's outer atmosphere (the corona*) is even hotter – about 2 million degrees Fahrenheit (1million degrees Celsius).The distance between sun and earth is expressed in ‘light years’.One light year is the distance travelled by light in one year.The speed of light is about 300,000 km /s.

Light from sun take about 8 minute to reach earthSo the distance is 8 light minutes

The distance to alpha centaury is about 4.3 light years

pole star is a visible star, preferably a prominent one, that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent position is close to one of the celestial poles, and which lies approximately directly overhead when viewed from the Earth's North Pole or South Pole (we feel it is still)

Constellations are groups of stars that forms a recognizable shapeconstellations were named by ancient

peoples. different cultures have identified and named star patterns. The Northern Hemisphere's constellations are named from Greek and Roman mythology. The Southern Hemisphere's constellations are named from instruments, objects, and animals that explorers encountered. The constellations were named between 1400-1700 A.D.

Some of the well known constellations are

Ursa Major (Big Dipper, Great Bear, Saptharshi)

Orion (Hunter)

Cassiopeia

Leo Major

We can see during summer time in the early part of the nightContains seven prominent starsAppears like a big ladle or a question mark, three stars in the handle and four in its bowlMoves from east to west around the pole starNot visible from some points in the southern hemisphere

We can see during winter in the late eveningOne of the most magnificent constellation in the skyContains seven or eight bright starsIt also called HunterThree middle stars represent the belt of the hunterFour bright stars appear to be arranged in the form of a quadrilateral

Brightest star in the skyLocated close to OrionIf we imagine a straight line from middle stars of Orion towards east we can locate the Sirius

In Northern skyVisible in winter in the early part of the nightLooks like a distorted letter W or M

A constellation does not have only 5-10 stars. It has a large number of stars . However we can see only the bright stars with our naked eye.All stars in a constellation is not same distance, only same line of sight in the sky