Astronomers last week announced the development of a new technique for measuring relative distances separating astronomical objects. It is expected to provide better estimates of the age and size of the universe.
The technique, developed by a team at the Massachusetts Institute of Technology and funded by the National Science Foundation, uses a combination of sensitive electronic detectors and statistics.
The researchers focused on 13 galaxies in the Virgo Cluster. "With this method, we don't see individual stars. We measure the average brightness of stars," said MIT's John L. Tonry.
The new method uses variations in the light recorded from a small piece of a galaxy and determines how many stars are in it. Tonry compared the technique to catching hailstones in empty paint cans.
In a field of cans, the number of hailstones falling in each will vary. After the stones have melted, the distribution of water varies more than if the same amount had fallen as rain drops. It is therefore possible to tell that a few large objects fell, rather than many small ones.
The astronomers can then divide the total amount of light by the number of stars to figure out the apparent brightness of an average star (the farther away it is, the fainter it appears).
They compare that figure with accepted estimates of the average actual brightness of stars in order to calculate how far away the galaxies are.