Photo of the Week. Mars (upper right) and Saturn
(lower left) make a fine pair, as seen the night of June 5, 2016. The
three-star head of Scorpius lies between them, while the red
supergiant Antares is near the
bottom edge. The fuzzy patch up and to the right of Antares is the
globular clusterMessier
4. See full resolution.)
Astronomy news for the two weeks starting Friday, July 1,
2016.
The next skylights will appear July 15.
As we begin, the Moon is in its waning
crescent phase, which is terminated at new Moon, when it
celebrates the Fourth of July. With a clear eastern horizon you
might catch a glimpse of the ultrathin crescent the morning of
Sunday, July 3. The Moon then switches sides, appearing as a very
thin waxing crescent in twilight the
evening of Tuesday the 5th, or at least by the following evening.
Watch as it climbs toward Jupiter,
gliding first south of the star Regulus in Leo the evening of Thursday the 7th then appearing just
to the west of the giant planet the following night and well to
the east of it a night still later. The crescent actually occults
Jupiter as seen from portions of the eastern hemisphere. The Moon
next takes a bead on two more planets, passing above Mars the night
of Thursday the 14th then above Saturn the
following night. After zipping through first
quarter the night of Monday the 11th, the Moon goes into its waxing gibbous phase, full Moon not reached until next week on
July 19. The Moon passes apogee, farthest from Earth, the night of
Tuesday the 12th. Regulus, Jupiter, Spica in Virgo, Mars, then finally Saturn make a semblance of a
dotted line that falls along the ecliptic, the apparent path of
the Sun
in late summer and autumn.
The three planets are putting on quite a show, starting with
Jupiter in the west as evening falls. As twilight draws to a
close, Mars shines already to the west of the celestial meridian. Saturn follows to
the east with the star Antares in Scorpius below. The trio of stars that makes the
Scorpion's head lies between the two planets. Jupiter sets shortly
before midnight, Mars around 2 AM, Saturn an hour later. Near the
two extremes of the Solar System, Mercury, quite out of sight, goes through superior
conjunction with the Sun on Wednesday the 6th, while just a day
later Pluto does the
opposite, going through opposition with the Sun on Thursday the
7th.
On the Fourth of July, only five hours after new Moon, the Earth
goes through aphelion, farthest from the Sun at a distance of
94.51 miles (152 million kilometers), just three percent farther
than its distance at perihelion in January, clearly showing that
the seasons have little to do
with solar distance but instead are caused by the 23.4 degree tilt
of the rotation axis against the orbital axis. Launched five years
ago, the spacecraft
Juno also celebrates the Fourth of July by entering orbit
around Jupiter, where it will observe the giant planet for the
next year and a half, giving us glorious views.
North of Mars, Saturn, and Scorpius a dark early-evening sky will
reveal the large distorted pentagon made by Ophiuchus, the Serpent Bearer, the
Serpent itself presented in two parts, the Head, Serpens Caput, to
the west of the Bearer, the Tail, Serpens Cauda, to the east.
Climbing the eastern sky is the Summer Triangle made of Vega in Lyra at the northwestern apex, Deneb in Cygnus at the northeastern, Altair in Aquila at the southern. High, nearly overhead, the Big Dipper descends to the
northwest.
