Explanation:
Clyde Tombaugh discovered
planet Pluto in 1930
while surveying the skies with the 13-inch Lawrence Lowell Telescope.
But the skilled and careful astronomer also went on to discover
star clusters, comets, asteroids, and clusters of galaxies.
For example, pictured is galactic or
open star cluster
Tombaugh 4 in the northern constellation
Cassiopeia.
Published in 1941, Tombaugh's
description, based
on his photographic images from the Lowell 13-inch, indicates the
cluster is small and faint, and comprised of about 30 stars.
Using the apparent brightness of the cluster stars
he estimated the distance to be 20 to 30 thousand
light-years, making Tombaugh 4 over 10 light-years in diameter.
This deep
color image, made with a modern ccd camera
and another 13-inch telescope, includes the region's
foreground stars and faint nebulosities.
