One Billion Light-Years

The 200-inch Hale telescope on Palomar Mountain has already proved itself astronomically successful. But with a little fixing it can do better still.

Astronomer Edwin Hubble told last week how he went to Palomar in January to put the great telescope through its paces. He knew already that the giant mirror and the intricate mechanism supporting it were good enough for nights when the "seeing" is only ordinary. On such nights the perfection of a telescope's performance is limited by irregularities in the air. Hubble wanted to try the great telescope on one of the rare nights (about 15 a year) when the stars hardly twinkle at all, and astronomers rejoice.

Feb. 1 was a pretty good night. Hubble pointed the telescope at a small patch of sky (Area No. 57 in the constellation Coma Berenices) that had been thoroughly studied through the old 1001nch telescope on Mt. Wilson. He started taking pictures. Results were good enough to excite the calmest astronomer.

In a six-minute exposure, the Palomar telescope recorded all that had ever been caught at Mt. Wilson. As the exposures were lengthened, fainter and more distant objects were found in constantly increasing numbers. An exposure of one hour brought in the "background," the shine of the night sky, and thus represented the maximum power of the telescope. To judge by the number of faint nebulae on it, this photograph reached one billion light-years (6 billion trillion miles) into space--twice as far as man had ever looked before. Said Hubble: "The tests confirm our previous conclusion that the Hale telescope is an unqualified success."

But the impresarios of the big eye will not repeat the error made at Mt. Wilson. When the 100-inch telescope was first used, it performed so well and the astronomers were so interested in what it showed that they would not let go of it. The final perfecting adjustments were not properly made for 15 years.

Optical experts know that the 200-inch Palomar mirror, even though it works well now, can work even better after a delicate repolishing of its outer ten inches. The great telescope will not start on its real program of charting the outer universe until it is as perfect as scientific skill can make it. The world's astronomers, impatient for news from a billion light-years away, do not mind waiting a little longer.

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