Saturday: Star light. Star bright. The first star you see tonight might be Vega, nearly seven fists held upright and at arm’s length above the eastern horizon right after sunset.
Sunday: Mercury will be as far away from the Sun in the sky
as it will get this orbital cycle. This "farthest away" point is
known as the planet's greatest elongation. Since Mercury is in the morning sky,
it is west of the Sun, and this occurrence is called the greatest western
elongation. This morning, Mercury is a half a fist above the east-northeastern
horizon at 5:00 a.m. Over the next few weeks, Mercury will move toward the Sun
in the sky. By mid-October, it will be visible in the evening sky.
Monday: Venus is a half fist above the western horizon at
9:30 p.m. Saturn is a half a fist above the eastern horizon and a half a fist
to the lower right of the Moon at 11:30 p.m.
Tuesday: It is often said that Earth is a water world
because about 70% of the Earth’s surface is covered by water. What would it
look like if all that water on the surface were gathered up into a ball? That
“ball” would be about 700 km in diameter, less than half the diameter of the
Moon. The Astronomy Picture of the day shows us right here https://apod.nasa.gov/apod/ap120515.html.
Wednesday: The Gemini twins, first Castor and then Pollux,
rise just before the Sun. At 5:00 a.m., Pollux is one fist above the
northeastern horizon. Slightly dimmer Castor is half a fist above it. Pollux is
the brightest star, as observed from Earth, known to have a planet orbiting it.
The planet, creatively called Pollux b, has about twice the mass of Jupiter.
Thursday: If you want to show your loved ones a celestial
sign that they should hang up their clothes, show them Brocchi's Cluster,
commonly known as the Coat Hanger cluster because of its resemblance to an upside-down
coat hanger. The cluster is about six fists above due south at 11:30 p.m.,
midway between Altair and Vega, the two brightest stars in the Summer Triangle.
You'll need binoculars to make out the shape. First find Altair five fists
above the southern horizon. Slowly move your binoculars up toward Vega. You
will run into the coat hanger along the way. And while you are at it, put away
your shoes.
Friday: Mars is three fists above the eastern horizon at
5:00 a.m. Saturn is four and a half fists above due south at this time.
The positional information in this column about stars and
planets is typically accurate for the entire week. For up-to-date information
about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
All times are Pacific Time unless noted.