What’s UpHighlighting the Near

and Deep Sky August 17, 2015 toSeptember 20, 2015

August 17th to September 20th

General Information

• August/September: • This remains a period best suited for viewing star clusters and

nebulae. Early on, most of the brightest galaxies (other than M31 and M33) are in the western sky.

• Three months past opposition, Saturn’s now in the western sky as darkness falls, with Neptune and Uranus the only other planets in the evening sky.

• Our view of the Milky Way begins a long transition from looking toward its inner arms and brighter regions to looking toward the outer, dimmer arms of the fall and winter ahead.

• Sunset Range: 8:09 p.m. (August 17th) to 7:20 p.m. (September 20th)

• End of Astronomical Twilight (Full Darkness* – Sun 18° below horizon): 9:45 p.m. (August 17th) to 8:48 p.m. (September 20th)

* Usually dark enough for observing about a half hour before this.

Moon Phases – August/September

• August 22nd – First Quarter Moon

• August 29th – Full Moon

• September 5th – Last Quarter Moon (Observing at Cahas on 4th and 5th)

• September 13th – New Moon (Observing at Cahas on 11th and 12th)

Roughly speaking:

• First Quarter Moon is highest at sunset and sets at midnight• Full Moon rises at sunset and is in the sky all night• Last (or “Third”) Quarter Moon rises at midnight and is highest at

dawn• New Moon sets with the sun and is absent from the sky all night

Celestial EventsAugust 17th to September 20th

• August 18th: Moon at apogee; distance 63.63 Earth radii.

• August 20th, 5:40 a.m.: Challenge Photo Op – Mars 0.22° S of Beehive Cluster (M44), 7° high in the east, one hour before sunrise.

• August 21st, 8:09 p.m.: Challenge Binocular Observation – Saturn at eastern quadrature. Find it at sunset, 90° from Sun, 33° high and 9° E of crescent moon, using arms and finger measurements.

• August 30th: Moon at perigee; distance 56.18 Earth radii (11.7% closer than August 18th apogee).

• September 1st, 4:00 p.m.: Equation of Time is 0.

• September 4th/5th, 12:35:20 a.m. (approx.): Challenge Telescopic Observation – In the east, occulted Aldebaran reappears from behind dark limb of the 5° high last-quarter moon.

• September 14th: Moon at apogee, distance 63.73 Earth radii; 2015 max.

Orbits and planet sizes not to scale

Mean Distance from Sun (AUs)

Mercury: 0.39 Jupiter: 5.20 Venus: 0.72 Saturn: 9.52 Earth: 1.00 Uranus: 19.20 Mars: 1.52 Neptune: 30.74 Pluto: 39.73

Planets’ Positions

July 20th (last meeting date)

August 17th

July 20th, 9:45 PMLast month’s meeting date.

Meridian

August 17th, 9:15 PM

Meridian

It’s getting darker earlier.

Saturn

Moon

August 17th, 9:15 p.m.

Sualocin

Rotanev

Delphinus

Great Sagittarius Star Cloud

NGC 6281

“Little Cat’s Eyes”(Mu Scorpii)

Moon

Saturn

Pluto

The “Teaspoon”

The “Teapot”

You’ve seen the movie.

You’ve even bought the T-shirt.

But now get prepared for the real . . .

Spaceballs

Sun

EarthJupiter

2mm bead

Earth

Moon

17 days to circumnavigate at 60 mph

5 years to circumnavigate at 60 mph

Key to Demonstrations – Help people relate to how much these objects shrink the reality.

Questions???