At this point, scientists realized that if they were to study the X-rays and other types of radiation emitted by stars, they would have to go high above the atmosphere. Stars with temperatures of several million degrees emit X-rays. So is the sun. In 1963, the United States launched a rocket and probed the Sun's X-rays with instruments on board.

Then in 1978 a satellite was launched to study X-rays emitted by stars.
Thus the branch of X-ray astronomy started in the field of astronomy. Later other sects appeared. NASA's high-altitude Chandra telescope has been studying X-rays from stars and making many new discoveries over the past several years.

Named after Indian-born and US-immigrated Nobel Prize-winning scientist Dr. S. Chandrasekhar, the flying telescope is abbreviated as the Chandra Telescope.

Several such flying telescopes have been launched over the years. These include the Hubble Telescope. It orbits the Earth at an altitude of about 560 km. The 11-ton telescope was launched in 1990. Fine dust in the atmosphere is a major nuisance for studying the sky. Hubble was paid for with this in mind.

Hubble has accomplished many feats over the years.
The Hubble Telescope also has facilities to study celestial objects that emit ultraviolet and infrared rays.

NASA later launched the GALEX flyby telescope in 2003 to capture and image the ultraviolet rays emitted by stars and galaxies. It operated until 2012 and sent several images taken in ultraviolet rays.

Many of the stars that are billions of years away may have planets, just like the Sun. It is impossible to find them on earth. So NASA commissioned the Spitzer telescope for this. It was paid in 2003.

This telescope has discovered many planets orbiting stars somewhere. It is designed to detect celestial objects that emit infrared radiation. It has completed the first phase and entered the second phase.

Now let's come to ISRO's Astrosat flying telescope. It is a telescope capable of capturing and examining everything that emits gamma rays, X rays, infrared rays, and ultraviolet rays. The instruments for that are housed in this flying telescope. In other words, this telescope will look at neutron stars, stars called pulsars, stars called white dwarfs, black holes, and the centers of the universe, which are highly energetic.

Apart from these researches, researches will also be carried out in conjunction with ground-based telescopes.
This is not the first time that India is involved in such research.

 Just as many countries used balloons and rockets in the early days to study X-rays emitted by stars, so did India. Besides, the IRS P-3 satellite launched by India in 1996 carried X-ray recording equipment.

The AstroSat flying telescope, now being launched, features instruments developed by experts from Canada and the University of Leicester in England. The Astrosat flying telescope cannot be compared to the Hubble, Chandra and Spitzer telescopes already flown by NASA.