In this article, we shall study about artificial satellites and their uses.

Natural satellites are heavenly bodies revolving around a planet in their fixed orbits. They are comparatively larger in size and their orbits have larger radii. Their surfaces are made of rocky mountains or gas.

Artificial satellites revolve around the earth much closer than the moon. They are man-made bodies fitted with sophisticated instruments and cameras and made to rotate around their planets in pre-fixed orbits. They are launched using rockets in the orbit from the earth.

Sputnik – I was the first artificial satellite launched on 4 th October 1997 by the Soviet Union. It was very small in size (58 cm in diameter), weighed only 83.6 kg. and took about 98 minutes to orbit the Earth on its elliptical path.

Yuri Gagarin of the Soviet Union of Russia was the first man to travel in space. A beach Lyka was the first animal to travel in a space.

Indian Progress:

Aryabhatta was the first Indian satellite launched on 19 th April 1975 by Russian rocket SOYUZ from the Russian launch pad at Baikonur. Some other artificial satellites are INSAT (Indian National Satellite), IRS (Indian Remote Sensing satellites) Kalpana – I, Edusat, GSat etc.

In India, the space research is done by ISRO (Indian Space Research Organization). ISRO’s CHANDRAYAN project has great success. It has found water on the surface of the moon for the first time. India had successfully launched a spacecraft called Mangalyaan to Mars.

Indian satellites are projected in the space from Shri Harikota near Andhrapradesh. This facility is also known as Satish Dhawan Space Centre. A new facility is coming at Chandipur in Orissa. India has developed series of rockets SLV (Satellite Launch Vehicle), ASLV (Augmented Satellite Launch Vehicle), PSLV (Polar Satellite Launch Vehicle), GSLV (Geostationary Satellite Launch Vehicle) etc. Using this technology we have developed missiles like Nag, Akash, Dhanush, Prithvi, Agni. Agni – III is ICBM (Intercontinental Ballistic Missile) with the range of about 5000 km.

Rakesh Sharma was the first Indian Astronaut to travel in space. Kalpana Chawla was first Indian origin US citizen to work in space.

Uses of Artificial Satellites:

• Making contact with things in space and for communication.
• Weather forecasting
• Telecommunications and broadcasting programs on radio and television.
• Conducting space research.
• Implementing educational programs.
• Making accurate maps.

Types of Satellites:

Communication Satellites:

A communication satellite is a satellite which revolves around the earth in earth’s equatorial plane in the same direction of rotation of the earth in 24 hours. The approximate height of such a satellite from the surface of the earth is about 36000 km. As it appears to be stationary with respect to an observer on the earth, the communication satellite is also called as the geostationary or geosynchronous satellite. e.g. INSAT series satellites.

Uses of Communication Satellites:

• They are used for sending microwave and TV signals from one place to another.
• They are used for weather forecasting.
• They are used for detecting water resource -locations and areas rich in ores.
• They  are used for spying In enemy countries i.e. It can be used for military purposes

Remote Sensing Satellites:

Remote sensing satellites study Earth’s surface from about a height of 480 km. These satellites are equipped with powerful cameras to scan the planet. The information of global environment, soils is sent to the base station on the earth where it is analyzed using computers.

Polar or Sun-synchronous Satellite:

A polar satellite is a low altitude satellite orbit around the earth in north-south orbit passing over the north pole and south pole. The orbit of the polar satellite is called polar orbit. The polar orbit makes an angle of inclination of 90° with the equatorial plane. Polar satellites cross the equatorial plane at the same time daily. The height of the polar satellite above the earth is about 500-800 km. Its time period is about 100 minutes.

Uses of Polar Satellite:

• Information gathered from polar satellites is extremely useful for remote sensing, meteorology as well as for environmental studies of the earth.
• They are used for spying and surveillance.
• They are used for monitoring troop movements i.e. for military purposes.
• They are used to note land and sea temperature variations.
• They are also used to monitor the growth of crops.

Global Positioning System (GPS):

The global positioning system is a system of several satellites that can give exact latitude, longitude and altitude of the place a person is located in. This system is used worldwide for navigation in airplanes, ships, cars, forests. India has developed its own navigation system called NAVIC.

Space Telescope:

Space telescopes are the satellites launched for observation of the space. Hubble telescope is such a space telescope. It observes the different ranges of radiation spectrum from outer space. Other examples of space telescopes are Chandra X-ray Observatory, Compton Gamma Ray Observatory and Spitzer Space Telescope.

The moon is not suitable as communication satellite.

It does not rotate in the equatorial plane of the Earth. It is not geostationary. that is its period is not of 24 hours. The distance between the moon and the Earth is very large. Hence the moon is not suitable as communication satellite.

Even as a Brazil-Germany Football match is played in Italy, we can watch it live at home

For such live telecast, geostationary satellites like INSAT are required. For such telecasts, we use indigenously launched satellites or we buy time slots on such satellites launched by other countries. These satellites are capable of transmitting signals from one place to other on the Earth.

Space Junk:

There are more than 8000 objects circling the earth. Not all these objects are working satellites. Such non-working non-useful objects are like debris in the space and are called space junk. They are orbiting around the earth at a speed of about 27,000 km per hour. Even a small piece of such object colliding with working satellite can damage the working satellite forever.

Radio Telescope (GMRT)

GMRT stands for Giant Metrewave Radio Telescope. The Tata Institute of Fundamental Research (TIFR) has set up this telescope close to the Pune-Nashik Highway at Khodad near Narayangaon. It helps in the study of the solar system, and its planets and satellites and related issues. It is the only telescope of its kind and scientists from all over the world come here to study the solar system, pulsars, supernovas, etc.

Food carried by Astronauts:

Astronauts carry both solid and liquid foods with them. They have their food directly from closed packets so that it does not fly into the air. This food provides them with all the food constituents and vitamins they need.

Science > Physics > Astronomical Physics > Artificial Satellites

The post Artificial Satellites appeared first on The Fact Factor.

The stars, the planets, the moon and many other objects in the sky are called celestial or heavenly bodies. The universe includes everything that exists. The branch of science that deals with the study of the universe is called astronomy. The Big Bang Theory is the most widely accepted theory about the origin of the universe. According to this theory, the universe emerged from an extremely dense and hot state. This was followed by a huge explosion, which gave birth to our universe, and it is assumed to be ever-expanding.

A cluster of stars is called Galaxy. A galaxy contains billions of stars. Galaxies exist in different shapes. The two most common shapes are elliptical and spiral. Our galaxy is a spiral galaxy. The galaxies having no specific shapes are called irregular galaxies. Our galaxy is called Milky Way (Akashganga). It consists of 100 billion stars including our sun. There are millions of galaxies like the Milky Way.

Earlier our ancestors learned about the celestial objects through direct and constant observation. At present we use three advanced techniques and methods to study celestial objects. These three techniques are:

• Use of telescope.
• Use of observatories with powerful telescopes
• By sending spaceships to distant planets.

Hubble telescope is the most powerful telescope in space.

The distance between the two celestial objects is very large. Hence it cannot be measured by using our practical terrestrial unit kilometre. The distance between celestial bodies is measured in a unit called a light-year. Though it contains the word year, it is not the unit of time. It is the unit of distance. Light moves at a velocity of about 300,000 kilometres per second. The distance that light can travel in one year is called the light year. So in one year, light can travel about 10 trillion km. More precisely, one light-year is equal to 9,500,000,000,000 kilometers.

Our Galaxy, The Milky Way:

It measures some 120,000–180,000 light-years in diameter. Our Solar System resides roughly 27,000 light-years away from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust particles called the Orion Arm.

Our galaxy is not perfectly disc-shaped but slightly warped.

Scientists believe that 90% of our galaxy’s mass consists of dark matter, which gives it a mysterious halo. The Milky Way has between 100 to 400 billion stars. The Milky Way is full of dust and gas. The Milky Way wasn’t always as it is today. It acquired its current size and shape by eating up other galaxies and is still doing so today. There is a black hole at the centre of the galaxy. Our Milky Way has been around for about 13.6 billion years. Its age is almost equal to that of the universe. The Milky Way, along with everything else in the Universe, is moving through space.

Constellations:

The stars forming a group that has a recognizable shape is called a constellation. The shape of the constellation remains the same. The constellations appear to move in the sky from the east to the west. Actually, the Earth rotates about its axis from the west to the east, hence we see the apparent movement of the constellations from the east to the west.

The constellations are named after observing their shapes and according to the prevailing beliefs or events. A constellation does not have only 5 to 10 stars. It has a large number of stars. However, we see only the bright stars in the constellation with our naked eye. All the stars which make up a constellation are not at the same distance. They are just in the same line of sight in the sky.

Constellation The Great Bear or Ursa Major or Great Dipper or Saptarishi:

The constellation we can see during summertime in the early part of the night is the Great Bear. The Great Bear is also known as Ursa Major or Great Dipper or Saptarishi. There are seven prominent stars in this constellation. It appears like a big ladle or a question mark. Three stars of this constellation are in the handle of the ladle and four in its bowl. A pole star can be located using this constellation.

Constellation the Orion:

The constellation Orion can be easily seen on winter late nights. The Orion is also called the Hunter. The three stars in the middle are said to be Orion’s belt. The Orion has seven to eight bright stars. If the line on the stars from the belt is stretched Eastwards it leads to the star called Sirius. Sirius is the brightest star in the sky.

Constellation Cassiopeia:

Cassiopeia is a prominent constellation in the northern sky which is visible during winter in the early part of the night. Cassiopeia constellation looks like the distorted letter W or M.

Constellation Scorpius:

It is one of the brighter constellations. Stars in this constellation form the image of a scorpion, with a long curving tail. From the northern hemisphere, Scorpius can be seen in the southern sky, close to the horizon. The Antares is the brightest star in the constellation Scorpius It marks as the heart of the scorpion.

International Astronomical Committee:

The whole sky is divided into 88 parts for convenience by International Astronomical Committee / Union (IAC or IAU). There are 37 constellations belonging to the northern sky and 51 constellations belonging to the southern sky.

Indian Contribution:

Ancient Indian astronomers had imagined 27 constellations which they called nakshatras.

Western and Tamil Names of Nakshatras:

Science > Physics > Astronomical Physics > Our Galaxy

The post Our Galaxy (Milky way / Akashganga) appeared first on The Fact Factor.