The Big Bang Theory is the cosmological model of universe that is best supported by all lines of scientific evidence and observations.

About 15 billion years ago a tremendous explosion started the expansion of the universe. At the point of this event all of the matter and energy of space was contained at one point, considered to be the beginning of the universe.

The key idea is that the universe is EXPANDING. Consequently, the universe was denser and hotter in the past and continues to this day.

GEORGES LEMAITRE ( 1894-1966)

A Belgian Catholic priest, cosmologist and scientist, proposed the Big Bang Theory of the origin of the universe in 1927.

Scientists built on his initial idea of cosmic expansion, which, his theory went, could be traced back to the origin of the cosmos and which led to formation of the modern universe.

THE BIG BANG THEORY

The Big Crunch is one of the scenarios predicted by scientists in which the Universe may end. Just like many others, it is based on Einstein’s Theory of General Relativity.

If the Big Bang describes how the Universe most possibly began, the Big Crunch describes how it will end as a consequence of that beginning.

It tells us that the Universe’s expansion, which is due to the Big Bang, will not continue forever. Instead, at a certain point in time, it will stop expanding and collapse into itself, pulling everything with it until it eventually turns into the biggest black hole ever.

THE BIG CRUCNH THEORY

The theory that proposes the historical origin of the solar system as a result of the collision of sun and a comet.

Proposed by Georges Leclerc, and Comte de Buffon.

A collision-encounter theory, proposed by T.C Chamberlain and F.R Moulton in early 20th Century.

It proposes that a star actually get close and collide with the sun.

Huge tides were raised on the surface; some of this erupted matter was torn free and, by a cross-pull from the star, was thrust into elliptical orbits around the sun.

The smaller masses quickly cooled to become solid bodies, called planetesimals. As their orbits crossed, the larger bodies grew by absorbing the planetesimals, thus becoming planets.

Scientists have suspected a star explosion called a SUPERNOVA, helped trigger our solar system’s formation. In particular, the shock wave

from the explosion is thought to have compressed parts of the nebula, causing these regions to collapse.

The planetary nebular theory is the most generally accepted evolutionary model for formation of the solar system from a cloud of gas and dust particles known as a NEBULA.

The process starts with a rotating cloud of gas and dust that contracts and flattens to form a disk around a star forming at its center. Planets grow from the dust and gas in the disk and are left behind when the disk clears.

A comet is known to be relatively small, solid body of frozen water, methane, carbon dioxide, and ammonia; along with the dusty and rocky bits of materials mixed in.

Became known to be “dirty-snowball”, coined by Fred Whipple.

This are the brilliant and most rare objects in the night sky. These soaring beacons with their beautiful tails come from chunks of rock and metal.

A spherical cloud of objects beyond the orbit of Pluto from about 30, 000 AU out to a light year of the sun and believed which comets aggregates. It is believed that there as many as 1 trillion comets in Oort Cloud.

This is understood that the Oort Cloud to be the source of long period comets, which orbital periods of more than 200 years.

A disk-shaped region of small icy bodies, which ranges 30-100 AU from the Sun.

This is understood that Kuiper Belt to be the source of short-period comets, which orbital periods of less than 200 years.

Nucleus of Comet Tempel 1 (9P/Tempel)

Credit: NASA / Deep Impact Spacecraft

They are made of rock, iron (troilite), dust and a variety of frozen chemicals including water and gases like carbon dioxide, nitrogen, carbon monoxide, ammonia and methane.

A comet nucleus can remain in a solid, pristine state, unobserved by even the world’s most powerful telescopes until it approaches a Sun.

It is the body of the comet.

A large lazy head around a comet.

Expelled water, dust, gas and debris form a fuzzy haze around the nucleus as nucleus get cold and eventually warm as it approaches to the Sun.

A comet’s coma can span a few miles in diameter to hundreds of thousands.

Formed due to the vaporization of ices from the heavier debris and particles.

The dust tail is primarily affected by the comet’s orbital path, which means this tail curves behind the nucleus as it orbits the Sun.

One of the most stunning recent examples of a comet with multiple dust tail was Comet McNaught (C/2006 P1),

which could be seen in the Southern Hemisphere in January of 2007.

It is formed when ionized gases are pushed directly away from the Sun by the Sun’s high speed solar wind.

The tails of a comet can be white, yellowish, blue, straight or curved depending on the comet’s chemical composition, vaporization, number of fragments, orbital path and movement in space relative to the Sun and Earth.

Hale-Bopp Comet on April 4, 1997.

Formed when coma and the nucleus fused together.

A large cloud of invisible hydrogen gas surrounds the head , and this hydrogen halo, may be hundreds of thousands of kilometers across.

The solar wind and solar radiation ionize gases and push particles from the coma pushing both into the familiar tail of the comet which is always pointing away from the sun.

COMET HALE-BOPP COMET MCNAUGHT HALLEY’S COMET

HYAKUTAKE COMET COMET LOVEJOY

Remnants of asteroids and comets.

These are small rocky or metallic body traveling through space.

The streak of light and smoke in the sky coming from a meteoroid as it move towards the Earth.

“shooting star” or “falling star”

Meteors burn up or evaporate completely within seconds after reaching an altitude of about 100km because they are no more than speck of dust.

Meteor shower occurs when Earth passes through a stream of particles left by a comets in its orbit.

Earth might meet the stream of particles concentrated in such an orbit on a regular bases as it travels around the Sun, resulting meteor showers.

NAME DATE OF MAXIMUM HOUR RATE

Quadrantid January 3 30

Aquarid May 4 5

Perseid August 12 40

Orionid October 22 15

Taurids November 1, 16 5

Leonid November 17 5

Geminid December 12 55

A meteoroid that survives its fiery trip through the atmosphere to strike the surface of the Earth.

These are classified into:

Iron meteorites Stony meteorites Stony-iron Meteorites

Small rocky bodies orbiting the belt between Mars and Jupiter.

These are also known as “planetoids” or “minor planets”.

These are composed of rocks, metals, and minerals.

The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars andJupiter.

It is occupied by numerous irregularly shaped bodies called asteroids or minor planets.

Discovered by Sir William Herschel in 19th

Century.

It is the largest asteroid, and the only dwarf planet in the inner Solar System.

It is composed of rock and ice, is 950 km (590 mi) in diameter, containing a third of the mass of the asteroid belt.

It was the first asteroid to be discovered, on 1 January 1801 by Giuseppe Piazzi.

CERES

VESTA The second-most-massive asteroid after the dwarf planet Ceres.

Has mean diameter of 525 kilometerss (326 mi) and was discovered by Heinrich Wilhelm Olbers on 29 March 1807.

Vesta is the brightest asteroid visible from Earth.

HYGEIA

Fourth largest asteroid in the Solar System by volume and mass, and it is located in the asteroid belt, with somewhat oblong diameters of 350–500 km and a mass estimated to be 2.9% of the total mass of the belt.

Observed and discovered by Annibale de Gasparis on 12 April 1849.

PALLAS

Third largest asteroid in the Solar System, and estimated to comprise 7% of the mass of the asteroid belt, and its diameter of 544 kilometers (338 mi).

Discovered by astronomer Heinrich Wilhelm Matthäus Olbers on 28 March 1802.

A massive, gravitationally bound system consisting of stars, stellar remnants, an interstellar medium of gas and dust, and dark matter.

It contain varying numbers of planets, star systems, star clusters and types of interstellar clouds.

Etymology:Derived from the Greek term for our own

galaxy, galaxias, meaning "milky one"), or kyklos ("circle") galaktikos ("milky") for its appearance

as a lighter colored band in the sky.

Elliptical galaxies are shaped like a spheroid, or elongated sphere.

These are given a classification that corresponds to their elongation from a perfect circle, otherwise known as their

“ellipticity”.

Elliptical galaxies have no particular axis of rotation.

Spiral galaxies have three main components:

BULGE: Is a spherical structure found in the center of the galaxy.

DISK: Is made up of dust, gas, and younger stars.

HALO: It is a loose, spherical structure located around the bulge and some of the disk. The halo contains old clusters of stars, known as globular clusters.

A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately two-thirds of all spiral galaxies.

Bars generally affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms

Irregular galaxies have no regular or symmetrical structure neither spiral or elliptical.

They are among the smallest galaxies and they contain a vast amount of gas and dust.

A spiral galaxy approximately 2.5 million light-years (2.4×1019 km)

from Earth.

It is similar to Milky Way’s size and shape, with about one hundred billion stars, gas and dusts turning in spiral pinwheel.

The Milky Way is a barred spiral galaxy with a flat rotating disc

consisting of gas, dust and stars which is estimated to be between 100,000-

120,000 light years across.

This disc is composed of the familiar spiral arms, one of which

plays host to Earth and other planets.

The nearest galactic neighbor for about 80,000 light years from the solar system.

It is called dwarf galaxy because it has diameter of only about 1,000 light years.

It is apparently in the process of being pulled by the gravitational pull of the Milky Way, which is now known to have eleven satellite galaxies.

An irregular galaxy which is also a neighboring galaxy of Milky Way.

Duo of irregular dwarf galaxiesvisible from the southern hemisphere, which are members of our Local Group and may be orbiting our Milky Way Galaxy.

Nearly 200,000 light-years from Earth, floats in space, in a long and slow dance around our galaxy.

It is a massive, luminous sphere of plasma held together by its own gravity.

These are most widely recognized astronomical objects, and represent the most fundamental building blocks of galaxies.

Stars are born from swirling clouds of hydrogen gas in deep space between stars. It consists of random, swirling atoms of gases that have little gravitational attraction for one another due to its mass.

Complex motions of stars causes shock wave causes the particles to move together, making compressions and began to form a cluster due to gravitational pull due to mutual gravitational attraction

A radiating ball and accumulation of cloud of gas formed due to the condensation of mutual gravitational attraction which further lead to the birth of a star.

As gravitational attraction accelerates the atoms towards the center , they gain kinetic energy and the interior temperature increases and after 10 million years of contracting and heating, the star is sufficient to perform nuclear fusion reactions.

As pressure increases fusion reactions for the next 17 million years, it will formed to an average star.

The difference of in brightness could be related to:

The amount of light produced by the stars.

The size of the star

The distance to a particular star.

measures the brightness of stars which is based on a system established by the Greek astronomer, Hipparchus.

TYPE COLOR TEMPERATURE (K) COMMENT EXAMPLE

O Bluish/Blue-Violet

30,000-80,000 Spectrum with ionized Helium and Hydrogen; short –lived rare stars

Mintaka(Oironis)

B Blue 10,000-30,000 Spectrum with neutral helium, none ionized

Rigel

A Bluish to White

7,500- 10,000 Spectrum with no helium, strongest hydrogen, some magnesium and calcium

Vega and Sirius

F White 6,000-7,500 Spectrum with ionizedcalcium, magnesium and

neutral atoms of iron.

Canopus

G Yellow 5,000-6,000 The spectral type of Sun. Shows sixty-seven (67)

elements in the Sun.

Sun, Alpha Centauri

K Red-Orange 3,500-5,000 Spectrum packed with line of neutral metals.

Arcturus, Aldebaran

M Red 2,000-3,5000 Band spectrum of molecules (i.e titanium oxide)

Betelgeuse

Major Stellar Spectral Types and Temperatures

Stars that are in the band of main sequence star are normal, mature stars, that are using their nuclear fuel at a steady rate.

Stars that are bright but low temperature; this are reddish stars are enormously bright for their temperature because they are very large, with an enormous surface area giving off light. This can be a hundred times larger than the sun but have the same mass of that of the Sun.

These are faint, white hot stars. It is faint because it is small, perhaps the size twice of the Earth and is also very dense and has mass approximately to the Sun.

Stars that change the brightness over a period of time. Cepheid Variable is a bright variable star that is used to measure distances.

Supergiants- 8-12 times larger than the Sun.

Brightest star in the southern constellation of Centaurus and the third brightest star in the night sky.

Its component stars are named Alpha Centauri A (α Cen A), with 110% of the mass and 151.9% the luminosity of the Sun, and Alpha Centauri B (α Cen B), at 90.7% of the Sun's mass and 44.5% of its luminosity.

Shot by Hubble Telescope

A red dwarf star which is approximately 4.24 light years distance from the Sun making it the closest and the nearest star from the Sun.

It is too faint to see in the naked eye with the apparent magnitude of 11.05.

Rigel, as seen from the RutherfurdObservatory on 09 September 2014

Is the brightest star in the constellation Orion and the seventh brightest star in the night sky, with visual magnitude 0.13.

A blue-white supergiant which is a triple star system with an absolute magnitude −7.84 and around 120,000 times as luminous as the Sun.

Astronomers calculate that Rigel is approximately 700 and 900 light-years away, with a temperature of 11,000K which puts up 400,000 times energy from the Sun.

Is the brightest star in the night sky, with a visual apparent magnitude of −1.46.

Sirius, a white dwarf star, is about twice as massive as the Sun and has an absolute visual magnitude of 1.42 and it is is 25 times more luminous than the Sun.

Sirius is also known colloquially as the "Dog Star", reflecting its prominence in its constellation, Canis Major (Greater Dog).

Is the brightest star in the southern constellation of Carina, and the second brightest star in the night-time sky, after Sirius with visual magnitude is −0.72, and it has an absolute magnitude of −5.65.

It is a supergiant star.

Is the ninth-brightest star in the night sky and second-brightest in the constellation of Orion.

The star is classified as a red supergiant and is one of the largest and most luminous observable stars.

Its distance from Earth was estimated in 2008 at 640 light-years.

Is the seventeenth brightest star in the night-time sky and the brightest star in the constellation Scorpius, and is often referred to as "the heart of the scorpion“.

It is red supergiant and one of the largest and most luminous observable stars.

Is an orange giant star located about 65 light years away in the zodiac constellation of Taurus.

With an average apparent magnitude of 0.87 it is the brightest star in the constellation and is one of the brightest stars in the nighttime sky.

Aldebaran is a slightly variable star.

Is the brightest star in the constellation Canis Minor; to the naked eye, it appears to be a single star, the eighth brightest star in the night sky with a visual apparent magnitude of 0.34

It is faint white dwarf star.

It is a main sequence star, or a G2 type yellow dwarf star.

Sun is the star at the center of the Solar System, and it is estimated to be 5 billion years old.

It has a diameter of about 1,392,684 km (865,374 mi), around 109 times that of Earth, and its mass (1.989×1030 kilograms, approximately 330,000 times the mass of Earth) accounts for about 99.86% of the total mass of the Solar System.

As the Sun grows old, it will expand. As the core runs out of hydrogen and then helium, the core will contact and the outer layers will expand, cool, and

become less bright. It will become a red giant star.

After this phase, the outer layers of the Sun will continue to expand. As this happens, the core will contract; the helium atoms in the core will fuse

together, forming carbon atoms and releasing energy. The core will then be stable since the carbon atoms are not further compressible.

Then the outer layers of the Sun drift off into space, forming a planetary nebula (a planetary nebula has nothing to do with planets), exposing the

core. Most of its mass will go to the nebula. The remaining Sun will cool and shrink; it will eventually be only a few thousand miles in diameter!

The star is now a white dwarf, a stable star with no nuclear fuel. It radiates its left-over heat for billions of years. When its heat is all dispersed, it will be a

cold, dark black dwarf - essentially a dead star (perhaps replete with diamonds, highly compressed carbon).

Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space and are named after mythological figures, animals or objects.

The brightest constellation is Crux (the Southern Cross).

The constellation with the greatest number of visible stars in it is Centaurus (the Centaur - with 101 stars).

The largest constellation is Hydra (The Water Snake) which extends over 3.158% of the sky.

There are over 88 named constellations.

Asterism is a pattern of stars recognized on Earth's night sky; it may form part of an official constellation, or be composed of stars from more than one.

Like constellations, asterisms are in most cases composed of stars which, while they are visible in the same general direction, are not physically related, often being at significantly different distances from Earth .

Popularized by Hans A. Rey, often called “The Virgins Diamond”.

It is composed of the stars Cor Caroli (in Canes Venatici), Denebola (the tail of Leo), Spica (the wheat of Virgo), and Arcturus (in Bootes). It is somewhat larger than the Big Dipper.

An East-West line from Arcturus to Denebola forms an equilateral triangle with Cor Caroli to the North, and another with Spica to the South.

The Arcturus, Regulus, Spica triangle is given the name “Spring Triangle ”.

The Summer Triangle is an astronomical asterism involving an imaginary triangle drawn on the northern hemisphere's celestial sphere, with its defining vertices at Altair, Deneb, and Vega, the brightest stars in the three constellations of Aquila, Cygnus, and Lyra, respectively.

This asterism as the "Navigator's Triangle".

The term was popularized by American author H.A. Rey and British astronomer Sir Patrick Moore in the 1950s.

The Winter Hexagon or Winter Circle/Oval is an asterism appearing to be in the form of a hexagon with vertices at Rigel, Aldebaran, Capella, Pollux, Procyon, and Siriusand it is mostly upon the Northern Hemisphere's celestial sphere.

On 1st magnitude Sirius, Procyon, Pollux, with 2nd-magnitude Castor -Capella, Aldebaran, and Rigel on the periphery, and Betelgeuse located off-center

The Procyon, Betelgeuse and Sirius triangle is given the name ”Winter Triangle”.

The Great Square of Pegasus is the quadrilateral formed by the stars α Pegasi, β Pegasi, γ Pegasi, and α Andromedae, representing the body of the winged horse

The asterism was recognized as the constellation ASH.IKU "The Field" on the MUL.APIN cuneiform tablets from about 1100 to 700 BC.

One of the brightest constellation in the southern sky.

CENTAURUS

Centaurus represents a centaur; a creature that is half human, half horse in Greek Mythology.

Notable stars include Alpha Centauri, which is the nearest star in the solar system.

CRUX

The Southern Cross, smallest yet distinctive constellation.

Its name is Latin for cross, and it is dominated by a cross-shaped asterism.

Known as Acrux, blue-white Alpha Crucis is the constellation's brightest star and the bottom star of the cross

Is constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology.

CASSIOPEIA

Notable stars include Alpha, Beta, Gamma, and Delta Cassiopeiae, forms the constellation Cassiopeia.

ORION

Prominent constellation located on the celestial equator and visible throughout the world.

It was named after Orion, a hunter in Greek mythology.

Its brightest stars are Rigel (Beta Orionis) and Betelgeuse (Alpha Orionis), a blue-white and a red supergiant.

URSA MINOR

A constellation in the northern sky, like the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the name Little Dipper.

Ursa Minor is notable as the location of the north celestial pole.

Polaris, the brightest star which is a yellow - white supergiant and brightest Cepheid variable star and notable to Little Dipper.

URSA MAJOR

A constellation visible throughout the year in most of the northern hemisphere;

(Latin: "Larger Bear"; also known as the Great Bear )

is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan.

CYGNUS

is a constellation in the northern sky, named after the winged horse Pegasus in Greek mythology.

PEGASUS

The WATER BEARER The RAM

The CRAB The SEA GOAT

The TWINS The LION

The PISCES The FISHES

The ARCHER The SCORPION

The BULL The VIRGIN