Photo of the Week. Mercury, seen in evening
twilight, can be remarkably bright - and then it is gone. Courtesy
of Robert H. Olley, with thanks.
Astronomy news for the two weeks starting Friday, May 20,
2016.
The next skylights will appear June 3.
We begin with the Moon late in its waxing
gibbous phase just a day shy of full,
which takes place the evening of Saturday, May 21, with the Moon
rising to the left of Mars and above
Antares and Saturn, the quartet making
a ragged box. By the following evening the Moon will be to the
left of Saturn, with Antares off to the right. The Moon then
drifts through its waning gibbous phase,
which ends at third quarter on Sunday the
29th, the near-perfect phase taking place near sunrise in North
America with the Moon high to the south. We then get to watch the
waning crescent, which closes out our
fortnight, new Moon taking place on Saturday, June 4. The morning
of Friday the 3rd the super-thin crescent will rise in morning
twilight just beneath Mercury,
providing a fine way to find the little planet. Binoculars would
be a good idea. Having passed apogee on Wednesday the 18th, the
Moon spends the entire fortnight moving slightly, about 11
percent, closer to Earth, passing perigee (nearest to Earth) on Friday the
3rd.
Already west of the celestial
meridian as the sky darkens, Jupiter dominates the
evening, setting roughly an hour past local midnight. Already up
in the southeast in evening twilight, Mars and Saturn make a fine
pair, Mars in fast
retrograde (to the west against the stars), Saturn
retrograding much more slowly to the east of Mars and to the
northeast of Antares, the trio making a very pretty sight,
especially when the Moon gets out of the way. Mars is in
opposition to the Sun on Sunday the 22nd, Saturn's opposition
following on Friday the 3rd. At those special times, the planets
will rise at sundown, cross the meridian to the south at local
midnight (approximately 1 AM Daylight), and set at sunrise. Mars,
now very bright and rivalling Jupiter, undergoes closest approach
to the Earth for this orbital round on Monday the 30th, when it
will be half an Astronomical Unit (Earth-Sun distance), 46 million
miles, or 75 million kilometers, from us. That closest approach is
8 days after opposition is the result of the eccentricity of the
Martian orbit. Not to be entirely left out, Venus goes through
superior conjunction with the Sun on June 6.
To the southwest of Jupiter lies Alphard, the luminary of Hydra, the Water Serpent, the name
from Arabic meaning "the solitary one," which has nothing to do
with a snake. To the northeast of the giant planet is Denebola, Leo the Lion's number two, the name referring to the
beast's tail, both stars about the brightness of Polaris, the North Star, which is
at the end of the handle of the Little
Dipper.
