Photo of the Week.. The Sun sets peacefully through
Astronomy news for the two weeks starting Friday, June
The next Skylights will appear July 7, 2017.
The last fortnight was the "bright run" with the Moon between first and
third quarters lighting up the sky and hiding the stars. Though the
full Moon is only a half-millionth as bright as the Sun, that is plenty
enough light to make a lot of observing impossible. This fortnight,
however, we encounter the flipside, the "dark run" between third quarter on Saturday the 17th near dawn
and first quarter the morning of Friday,
June 30, these two phases now centered on new Moon, which is passed on
Friday the 23rd. In between third
quarter and new, on Tuesday the 20th, the waning crescent Moon will make a fine sight
Venus to the left, while by the next morning the Moon will have
slipped another 13 degrees along its path and will be down and to the
left of the brilliant planet, which rises just as the first glimmer of
dawn begins to light the eastern sky. Shifting your gaze to the west to
waxing crescent will yield a memorable
sight when it is seen just south of Regulus in Leo.
The Moon passesperigee, where it is
closest to the Earth in its eccentric orbit, on Tuesday the 27.
Jupiter, the brightest body in the evening sky (the planet in Virgo northwest of Spica), sets about an hour after Saturn rises in
the southeast between Sagittarius and Scorpius. After another hour and a half, Venus
rises, its luster putting all the other planets to shame. Going deeper
into the Planetary System,
Mercury goes through superior conjunction with the Sun (on the other
side of it)on Wednesday the 21st.
The big event, though, involves Earth, when at 11:24 PM on Tuesday the
20th (11:24 AM EDT
Wednesday the 21st), the Sun passes the Summer Solstice at
the most northerly part of the ecliptic, 23.4 degrees north of the equator. On this longest day (and shortest
night), the Sun will rise as far northeast (and set as far northwest) as
possible, and pass overhead at the Tropic
of Cancer (thus defining the Tropic's latitude). North of the
Tropic, the Sun will also cross the meridian
as far north as possible, giving us the maximum heating rate and, of
course, the first day of astronomical Summer. Traditionally the Solstice
lies in the constellation Gemini, but around
1930, the 26,000 wobble (precession) of
the Earth's axis brought it across the border with Taurus established in 1930.