(Above: Features visible on a full moon are labelled on this image by Michael Watson of Toronto. The Apollo Mission landing sites are the red numerals. Apollo 11 was sent to study the dark, bluish basalts of Mare Tranquilitatis.)
Hello, Summer Stargazers!
Here are your Astronomy Skylights for the week of July 14th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory or the David Dunlap Observatory, visit www.astrogeo.ca.
I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!
The Moon and Planets
This week, a big, bright moon will dominate evening skies all over the world – perfect for reminding us to celebrate humankind’s first steps upon it 50 years ago this Saturday, July 20 when Apollo 11 landed on the moon. Besides that, there are plenty of other celestial doings to look at. Here are the Skylights!
When the bright, nearly full moon rises over the southeastern horizon at 8:30 pm local time on Monday evening, the medium-bright, yellowish planet Saturn will be positioned 2.5 finger widths to the left (celestial east) of it. The pair will cross the sky together during the night and will easily fit within the field of view of your binoculars. If you watch the pair over several hours, starting at dusk, you will see the moon’s orbit carry it closer to the planet and the rotation of the sky lift Saturn above the moon. Observers in eastern Melanesia, southern Polynesia, Easter Island, and central South America will see the moon cover (or occult) Saturn.
The July full moon will happen at 5 pm EDT on Tuesday. Also known as the “Buck Moon”, “Thunder Moon”, or “Hay Moon”, this one always shines in or near the stars of Sagittarius (the Archer) or Capricornus (the Sea-Goat). When the moon approaches its full phase, all of the regions where the Apollo astronauts explored are illuminated by sunlight. Each of the six crewed Apollo Missions was sent to a different region of the moon in order to carry out experiments and to bring back rock samples that help us determine the age and composition of the moon’s surface. For safety reasons, Apollo 11 was sent to the flat and relatively featureless terrain of Mare Tranquillitatis “Sea of Tranquility”. Later missions landed in more rugged regions with complex geology. Visually, Mare Tranquilitatis is darker and bluer than the other mare – due to a higher Titanium content in the basalt rocks that created it.
This full moon will also feature a partial lunar eclipse. The northern portion of the moon will pass through the southern edge of Earth’s umbral shadow and become darkened. At greatest eclipse, the moon will be in Sagittarius and positioned 7.5 finger widths east of Saturn. The entire eclipse will be visible from most of Africa, the Middle East, and western India. South America will see the later stages of the eclipse after moonrise, and Australia and Southeast Asia will see the eclipse set in progress. None of the eclipse will be visible from North America. Maximum eclipse occurs near Maputo, Mozambique at 21:30:46 UT. Remember that lunar eclipses are completely safe to watch without eye protection.
(Above: This is the arrangement of the sky that was seen by observers near Toronto at the moment Neil Armstrong was stepping on the moon - at 10:56:15 pm EDT.)
After Tuesday, the moon will wane in phase and rise later – passing through the stars of Capricornus and then Aquarius (the Water-Bearer) on the coming weekend. Unfortunately, the moon will rise very late on the anniversary date.
Mars is steadily fading from view as it slips downward towards the evening sun. Your best chance to see it will be low in the north-northwestern sky before about 9:30 pm local time. Thankfully, we’ve got the two big gas giant planets to view in evening this summer.
The incredibly bright object gleaming in the southeastern evening sky is Jupiter! This week, Jupiter will be visible from dusk to about 3 am local time. Even a backyard telescope can show Jupiter’s two main equatorial stripes and the four Galilean moons named Io, Europa, Callisto, and Ganymede. They always appear in a rough line flanking the planet. If you see fewer than four, then some are either in front of Jupiter, or hidden behind it.
(Above: On Monday, July 15, the waxing gibbous moon will land near Saturn, as shown here for 10:30 pm EDT. Jupiter is off to the west.)
From time to time, the small, round black shadows cast by the Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. Europa’s shadow will be transiting Jupiter from 9:09 to 11:38 pm EDT on Tuesday with the Great Red Spot, and Io’s shadow will cross on Saturday, July 20 from 8:54 to 11:06 pm EDT.
Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Tuesday evening from 8 to 11 pm EDT. More GRS viewing opportunities will occur from 9:45 pm to 12:30 am on Thursday night, and after dusk on Sunday.
Yellow-tinted Saturn will remain visible all night long during August. Its position in the sky is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 3 fist diameters to the lower left (east) of Jupiter. Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn’s rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s is), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from Saturn’s upper left tonight (Sunday) to below the planet next Sunday. (Remember that your telescope will flip the view around.)
For night owls, distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising shortly at about 11:30 pm local time this week. You’ll find the magnitude 7.9 planet sitting a thumb’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii.
Blue-green Uranus will be rising at about 1 am local time this week. It is sitting below the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is bright enough to see in binoculars.
(Above: Venus will soon vanish into the pre-dawn twilight. for now you can still look for it low in the ENE, as shown here at 5:30 am local time.)
Similar to Mars, Venus is barely bright enough to see within the pre-dawn twilight sky that surrounds it, but it is sitting very low in the northeast - sinking ever-closer to the rising sun. Venus will be rising at about 5 am local time all week.
Finally, Pluto reaches peak visibility today – but invisible to backyard telescopes.
Some Moonlight-Friendly Sights
If you missed last week’s suggestions for objects to look for on moonlit nights, I posted the sky charts here.
Public Astro-Themed Events
At 7:30 pm on Wednesday, July 17, the RASC Toronto Centre will hold their free monthly Recreational Astronomy Night Meeting at the Ontario Science Centre, and the public are welcome. Talks include The Sky This Month (presented by me), imaging planets while at southern locations, and solar science. These meetings are also streamed live on RASC-TC’s YouTube channel. Check here for details. Parking is free.
Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here.
On Tuesday, July 16 and Thursday, July 18, starting at 11 am, U of T’s AstroTour planetarium show will be a Kids Summer Break Show. Find tickets and details here.
At 3:30 pm on Tuesday, July 16, the Agincourt Library will present a free public talk by Max King from the University of Toronto’s Astronomy & Astrophysics department entitled Mission to Pluto, From Napkin to New Horizon. Check here for details.
On Tuesday, July 16, starting at 7 pm, U of T’s AstroTour planetarium show will be Our Musical Universe. Find tickets and details here.
(Above: One of few photographs of Neil Armstrong on the moon, taken by Buzz Aldrin.)
The 50th Anniversary of humankind’s first steps upon another world is here! Here is a list of the places around town where you can join experts and fellow “lunatics” to honour Apollo 11 this Saturday night, July 20.
On Tuesday, July 16, starting at 8 pm, York University’s Allan I. Carswell Observatory will celebrate the 50th Anniversary of Apollo 11 with a free film and star-gazing on the Arboretum roof! Details are here.
Ontario Science Centre: Apollo 11 50th Anniversary on Saturday from 10 am to 10 pm features many moon and space activities and presentations, stargazing – and a Canadian astronaut! Regular admission and parking fees apply, except for the star party. Details are here.
Aga Khan Museum: Moon Landing Festival on Saturday and Sunday from 12 pm to 10 pm features art, live music, talks, and stargazing. Free! Details are here.
U of T’s Dunlap Institute: SpaceTime on Saturday from 6:30 to 8:30 pm features all-ages fun, talks, games, and giveaways. Free! Details are here.
The next RASC Family Night at the David Dunlap Observatory will be on Saturday, July 20. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!