Highlighting the Near and Deep Sky What’s Up E W Highlighting the Near and Deep Sky July 1 - 31, 2018 S

General Information July 2018 Among July’s celestial happenings: Earth reaches an orbital milestone. Partial solar and total lunar eclipses occur. (Yay!) But neither is visible in the U.S. (Boo!) The Red Planet gets to strut its stuff. Sunset Range: 8:44 PM (July 1st) to 8:28 PM (July 31st). End of Astronomical Twilight*: 10:37 PM (July 1st) to 10:10 PM (July 31st). * This is “full darkness” – the sun has reached 18° below the horizon. It’s usually dark enough for observing about a half hour before this. THIS IS THE REAL DEAL!!!

Moon Phases July 2018 Fri., 6th – Last Quarter (Fri./Sat. observing opportunities July 6th/7th) Thurs., 12th – New Moon (Fri./Sat. observing opportunities July 13th/14th; partial solar eclipse – only visible in southern Australia and Pacific) Thurs., 19th – First Quarter Fri., 27th – Full Moon (Total lunar eclipse – visible in eastern Africa and Mediterranean to India, from central Russia to Antarctica) 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 (“Third”) Quarter Moon rises at midnight and is highest at dawn New Moon sets at sunset and is absent from the sky all night

Celestial Events July 2018 Fri., 6th – Earth at aphelion, 1.0167 AU from the Sun. Tues., 10th – Venus 1° NNE of Regulus in evening sky; magnitudes – 4.1 and 1.4. Tues., 10th – Jupiter stationary in r. a.; resumes direct (eastward) motion. Had been moving in retrograde (westward) since March 9th. Fri., 13th – Moon at perigee; distance 56.04 Earth-radii. (Second nearest for 2018; closest was January 1st, 55.91 Earth-radii distance.) Thurs., July 26th – The Equation of Time reaches a shallow minimum of 6.54 minutes. Thurs./Fri., 26th/27th – Mars reaches opposition just 4 nights prior to its closest approach to Earth and less than two months from perihelion. More on Mars shortly. Fri., July 27th – Moon at apogee; distance 63.69 Earth-radii. (Second farthest for 2018; farthest was January 15th, 63.73 Earth-radii distance.) Image Credit: Clem Rutter, Rochester, Kent, UK, 2011; originally from nl.wikipedia, 2005, by Willie Leenders

(~30 min. before full darkness) (~30 min. before full darkness) July 15th, 9:00 p.m. (~30 min. before full darkness) July 15th, 10:00 p.m. (~30 min. before full darkness) For tonight, Mar. 19th, 8:30 p.m. is about 30 min. before full darkness. For tonight, July 18th, 10:00 p.m. is also about 30 min. before full darkness. Moon E Venus W Jupiter Mars Saturn S

Mars at Opposition July 27, 2018 Mars at Opposition July 27, 2018

Mars Opposition Factinos This is the first perihelic opposition of Mars since August 2003, which was the closest it had come to Earth in nearly 60,000 years. On July 27th, Mars will be only 0.8” smaller in diameter than in 2003. On July 27th, the night of its opposition, Mars (mag. -2.78) will be about twice as bright as Jupiter (mag. -1.98) and will nearly equal the maximum brightness Jupiter ever attains (mag. -2.94). On July 27th, Mars will be about 7° SE of the nearly full moon. Closest approach to Earth is on July 31st, when it will be 35,786,127 miles away, about 60,000 miles closer than on the 27th.

Mars Observing Info Date Rises Diameter Magnitude June 1 12:25 AM 15.5” -1.22 June 18 11:31 PM 18.4” -1.75 July 1 10:44 PM 20.9” -2.16 July 15 9:47 PM 23.2” -2.57 July 27 * 8:52 PM 24.3” -2.78 August 21 6:55 PM 22.5” -2.37 September 16 ** 5:15 PM 18.5” -1.68 * Date of opposition ** Date of perihelion

? Mars Question We just said . . . Question: “Closest approach to Earth is on July 31st, when it will be 35,786,127 miles away, about 60,000 miles closer than on the 27th.” Question: What, then, accounts for Mars being slightly dimmer (mag. – 2.77) on the 31st than on the 27th (mag. – 2.78)?

Stargazers Online

Parting Shot Apple Ridge Farm celebrated its 30th Homecoming on Saturday, June 9th. Earlier in the day, RVAS Immediate Past President Dan Chrisman and ARF Board Member was on hand and is seen here securely bolting down the solar panel onto the ARF/GE Observatory, to prevent it from pulling away again. Photo by Michael Good, RVAS Past President and ARF Board Member

What’s Up programs are posted on the RVAS Website! Questions ??? What’s Up programs are posted on the RVAS Website!