Courtesy of EarthSky
A Clear Voice for Science
www.EarthSky.org
Where is the Milky Way these days? That faint luminous band of stars crossing the dome of sky is nowhere to be seen on May evenings. Why?
The disk of our Milky Way is shaped like a pancake. On May evenings, the plane of the pancake-shaped galactic disk coincides with the plane of the horizon. Because the Milky Way disk sits along the horizon in every direction, the Milky Way doesn’t appear in the sky on May evenings.
The galactic disk most closely aligns with the horizon at about 30 degrees north latitude – the latitude of St. Augustine, Florida. Appreciably north of this latitude, the galactic disk tilts a bit upward of the northern horizon. Appreciably south of 30 degrees north latitude, the galactic disk tilts a bit above the southern horizon. Even so, the Milky Way is pretty much out of sight.
Like the sun, the stars rise in the east and set in the west. If you stay up until after midnight, you will eventually see the stars of the Summer Triangle – Deneb, Vega and Altair – rising above your eastern horizon. In a dark country sky, the Milky Way’s band of stars becomes visible as well, for the Milky Way passes right through this triangle of stars.
Written by Bruce McClure
Astronomy Picture of the Day from NASA/JPL
U.S. Naval Observator Astronomical Information center
The York County Astronomical Society
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