Chapter 4-10

What's coming

The next major development in Space Age astronomy will be the launching of the Space Telescope in the mid-1980's. We will finally have an optical telescope above the disturbing influence of the atmosphere, thus increasing the sharpness of images and allowing us to see more distant galaxies than can be photographed, even with larger telescopes, from the ground. The Space Telescope will be able to tell a spiral galaxy from a barred spiral galaxy at a distance of 5 billion light years, or take photographs of Mercury from Earth orbit that show as much detail as those made from Mariner 10, when it flew past the planet.

After Space Telescope, the next major astronomy mission planned is the Gamma Ray Observatory (GRO). This satellite will carry instruments designed to detect gamma rays over the entire range of energies from a few hundred to several hundred million kilovolts. The GRO will be a powerful tool for investigating the most baffling and puzzling objects in space: pulsars, quasars, and active galaxies.

To learn more about dust in the universe and about the whisper from the Big Bang, we are developing or biting infrared telescopes. There are still some technical problems. For example, infrared detectors have to be kept very cold, which is surprisingly difficult on an Earth-orbiting space craft. The first planned NASA mission is called IRAS (for Infrared Astronomy Satellite); it will carry a small telescope in a low-temperature chamber. Later, a Spacelab Infrared Tele scope Facility (SIRTF) will be deployed on the Space Shuttle. With these instruments, we can study for the first time the coolest matter in our galaxy: the clouds of interstellar molecules and the dense condensing masses of dust and gas from which stars are born. The Cosmic Back ground Explorer (COBE) will concentrate on the study of the microwave background and other sources of widely distributed infrared and microwave radiation. Planning now calls for a launch in the late 1980's for a mission that will last about one year.

The advance of Space Age astronomy is being supported by new instruments on the ground, notably the Very Large Array (VLA) of radio telescopes in New Mexico. The VLA consists of 27 radio dish antennae that simulate a single radio telescope 31 kilometers in diameter. This same principle, that a set of small radio telescopes can be designed to act like a very large telescope, may eventually be exploited in space. Operating a radio telescope in orbit in conjunction with radio telescopes on the ground would produce a system that acts in some respects like a radio telescope larger than Earth! At the same time, new techniques in photography and in electronically recorded optical images are greatly improving the speed and sensitivity of astronomical observations made on the ground.

Space Age astronomy is a joint effort of all astronomers to elucidate the nature of the universe. In spite of all that we have learned in the last few years, we have only just begun to see.

Table I
Typical dimensions of the stars
Star Mass (Mass of Sun = 1) Diameter (km) Diameter (miles)
Normal Stars:
Red dwarf 0.1 180,000 112,000
Sun 1 1,390,000 864,000
Sirius 3 3,200,000 2,000,000
Young blue star 18 10,000,000 6,200,000
Evolved Giants:
Red Giant 6 35,000,000 22,000,000
Red Supergiant 20 1,000,0001000 620,000,000
Dying Stars:
Black hole 4 24 15
Neutron star 1.5 20 12
White dwarf 1 20,000 12,000
Planetary Comparisons:
Earth: 0.000003 12,760 7,930
Jupiter: 0.001 143,000 89,000
Earth's orbit: - 299,000,000 186,000,000

Selected Readings

Friedman, H. 1975,
The Amazing Universe
(Washington, D.C.: The National Geographic Society).

Kaufmann, W. J. 1978,
Stars and Nebulas
(San Francisco: Freeman).

Maffei, P. 1978,
Beyond the Moon
(Cambridge, Mass.: MIT Press).

Rowan-Robinson, M. 1979,
The Cosmic Landscape
(Oxford: Oxford University Press).

Sullivan, W. 1979,
Black Holes: The Edge ofSpace, the End of Time
(New York: Doubleday).

Weinberg, S. 1977,
The First Three Minutes
(New York: Bantam).

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