PHM Planetarium &
Transit of Mercury
The PHM Planetarium celebrated the 2006 transit of
Mercury, when the silhouette of Mercury was visible by day as it passes
directly between the earth and the sun! Images of the event are at mercury-images.htm.
Tuesday, November 7, at 6:30 p.m.
A special program in the planetarium conveyed the significance of the transit, what observers can expect to see, and
insight into the planet closest to the sun. Three transit of Mercury
artifacts (below) were on display.
Wednesday, November 8, from 1:00 p.m. to about 5:00
apparent diameter is so small, seeing the transit requires a
magnified view through a proper solar filter. The planetarium and local amateur astronomers
had a variety of solar-filtered telescopes available for the public to view the transit live. All programs
Thank you, Lou, Linda, and Nick, for your support with the
Hydrogen-alpha telescope shows solar prominences and surface
8-inch reflector telescope has white light filter to show Mercury
80mm reflector telescope offers viewing through white light filter.
Sunspotter projects solar image onto white surface.
Orange C-8 scope is atop a convenient German equatorial mount.
Rear screen projection allows multiple observers around one
Bring your art supplies so you can enter your photo or drawing of the transit of Mercury as seen through a
Hydrogen-alpha telescope in this contest. Submissions are due November 13,
at YMCA Camp Eberhart will kindly provide the H-alpha telescope used outside
the PHM Planetarium.
First contact: 2:12:24 p.m. EST
Mercury Azimuth: 207° 47.38'
Mercury Altitude: 26° 41.32'
Hour Angle: 1h 43m 36.7s
Right Ascension (J2000): 14h 55.40m
Declination (J2000): 116° 52.06'
Diagram courtesy of Fred Espenak.
The PHM Planetarium & Air/Space Museum will have
three transit of Mercury items on display:
-Atlas Coelestis, Plate 7 by Johann Doppelmayer, 1742;
-Durchgang de Mercur by Wilhelm Nitschke, ca.1852;
-Reports on Telescopic Observations of the Transit of Mercury, May 5-6,
1878 by the US Naval Observatory.
In 1742, Johann Doppelmayer features transits of Mercury and Venus in Atlas
Coelestis while describing phenomena associated with the inferior
planets (Plate 7).
Doppelmayer illustrates the path of Mercury across the face of the sun for
the November 6, 1720, transit of Mercury.
Inset shows personified Mercury and Venus passing between the earth
and the sun, depicting the circumstances that create a transit.
Durchgang de Mercur by
Wilhelm Nitschke, ca.1852.
Reports on Telescopic Observations of the Transit of Mercury, May 5-6,
1878. Includes individual reports from Asaph Hall, William
Harkness, J.R. Eastman, Edward S. Holden, and Dr. Henry Draper.
Because "the cusps will appear undulating and diffused; and for a few
seconds it will be doubtful whether contact has or has not taken place...the
best the observer can do is watch for the phase represented by disk I...The
moment of true contact is that at which the undulation of true sunlight across
the dark space is just beginning."
Arrangement of Dr. Henry Draper's equatorial-room and of the instruments
at Dr. Draper's Observatory.
The black drop effect is attributed to "a
very variable amount of irradiation of bright images on the retina,"
though with caveats.
During the transit, Mercury appears as a tiny dot slowly
gliding across the face of the sun. In 1716, young astronomer Edmund Halley
witnessed a transit of Mercury and recognized that a transit of an inferior
planet could be used mathematically to measure the distances of the planets from
the sun. Decades later he advocated using a transit of Venus to quantify
the size of the solar system. See www.transitofvenus.org/sitemap.htm
for more details about these rare celestial alignments.
Located at Bittersweet School just north of Penn High School, the planetarium
featured extensive programs and observing opportunities
for the 2004 transit of Venus. The next transit of Venus will be in June
2012; the next transit of Mercury will be in May