Big, big, universe


Martha’s Vineyard, with a clear horizon and relatively little light pollution to the south, makes a fine platform for viewing celestial wonders.

This week, exceptionally clear nights with no moon offered great views of the Milky Way. From almost any vantage point on the south side of the Island, our galaxy is easily visible with the naked eye.

This photo of Edgartown Light was taken about 4:10 am on April 16.

For photographers, it is a 10 second exposure at f/3.5. ISO was set at 6400, with a zoom lens at 18 degrees. The camera is a Nikon D7000.

For non-photographers, that means the camera settings were optimized to gather as much light as possible through the lens and collect it onto the digital camera sensor.

If you are not an early, early, early riser, wait until fall and the same view will appear in the evening, after the sky gets completely dark on nights when there is no moon.

Our sun is one of approximately (no one has actually counted them) 300 billion stars in the Milky Way, located about two-thirds of the way out from the center of the galaxy.

From this vantage point, looking back toward the center of the galaxy makes the concentration of stars appear as a “milky” band.

The dark regions within the Milky Way are areas where stellar dust blocks light from the stars.

It takes about 100,000 years, at a speed of 186,282 miles per second, for light to travel from one edge of the galaxy to the other.

In 1610, using a new-fangled invention called a telescope, Galileo proved that the faint cloudy band in the sky is made up of individual stars.

About 300 years later, astronomer Edwin Hubble used a much more sophisticated telescope to demonstrate that the Milky Way is one of many galaxies in the universe.