But in the 1970's, Dr. Frank Drake, an astronomer who has long advocated a systematic search for intelligent extraterrestrial life, proposed a way around the difficulty.

One amateur astronomer, Reiner M. Stoss, even proposed Sedna as a name for a small, earlier discovered asteroid, to thwart Dr. Brown.

But this is not what is observed in spiral galaxies; instead, astronomers propose that the spiral pattern is a density wave emanating from the Galactic Center.

Some astronomers proposed long ago that starlight must be absorbed by dust in the vast reaches of interstellar space.

Recently, astronomers have proposed a new glue for the universe, dark energy.

In the thirteenth century the astronomer, al-'Urḍi, proposed a radical change to Ptolemy's system of nesting spheres.

The astronomer did not propose to wait decades for new evidence from the Net.

Though Savage-Smith asserts that no Islamic astronomers proposed a heliocentric universe.

Since the 1870's when French astronomers proposed the idea, it has sometimes been suggested that the dark patches represent vegetation.

To make up for these limitations, astronomers have proposed larger and more ambitious projects.