Distances of the Stars.

Te Aroha News, Volume VIII, Issue 485, 2 July 1890, Page 6

Distances of the Stars.

Only Forty Have Been Measured Out of Forty Million Shining Worlds.

As the observer on a brilliant star-lit night looks upward to the grand concave above him, studded with shining orbs, various questions arise in his mind. He wonders if the brightest sturs aro nearer to us than those that give less light, and if science shows any way for finding the distances of the stars.

The same question puzzled astronomers for centuries in the early history of the science. Happily, these questions are now solved. The brightest stars are not always the nearnest, and the distance of a small number of stars has been approximately measured. This means that about twenty stars are found to have a measurable paral* lax, or to show a displacement when, the earth is in opposite points of her orbit. The work of measuring stellar parallax is the most delicate of the whole range of practical astronomy. It was trisd repeatedly from the day of Tycho Brahe down. Even the great Herschel failed to detect the least displacement, for the telescopes of the time were not delicate enough to measure the parallax ot a star. Bessell, however, in the year 1838, succeeded in measuring the parallax of 61 Cygni, a double star of the fifth magnitude in the constellation of the Swan. This little star, barely visible to the naked eye, is the earth’s nearest neighbour in the Northern Hemisphere ; butnearas it is, it takes light more than seven years to span the intervening distance. If the tiny star were blotted from the sky to-day, its hghtwould continue to come to us for more than seven years.

Henderson, in 1839, at the Cape of Good Hope, determined the distance of Alpha Centauri, a double star of the first magnitude in the Southern Hemisphere, ranking noxt to Sirius and Canopus in brilliancy. This radiant star is about half the distance of 61 Cygni, and its light reaches the earth in about four years. It is therefore, as far as is known, the nearest star to the earth. The work of measuring the distances of the stars went steadily on after this brilliant commencement, and there are now about twenty stars whose distances are approximately known. Among them are Sirius, the fourth in the order of nearness, requiring a light journey of ten years; Aldebaran, requiring fourteen years ; and Arcturus, thirty-five. There are perhaps twenty othei’s whose measured distances are not considered trustworthy, making forty stars, of which the parallax has been detected forty among 40,000,000. The overwhelming majority aro so remote as not to show the slightest trace of optical shifting under the scrutiny of the most powerful instruments. —■ Youth’s ConiDanion.’