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RASC Calgary Centre - Current Astronomical Highlights by Don Hladiuk RASC Calgary Centre - Current Astronomical Highlights by Don Hladiuk Follow Don on: ("astrogeo") ASTRONOMICAL HIGHLIGHTS provides information about space science events for the upcoming month. The information here is a rough transcript of information covered on the popular CBC Radio One Calgary Eyeopener segment on 1010 AM and 99.1 FM usually on the first or second Monday of each month at 7:36 AM. Don is a life member of the Royal Astronomical Society of Canada and was twice President of the Calgary Centre. Since June 1984, Don has had a regular radio column on the Eyeopener describing monthly Astronomical Highlights to southern Albertans. For additional sources of sky information see the list of links below this month's article. For information about the Calgary Centre of the RASC, please visit our web site. Interested in Astronomy? Become a member of the RASC! Click here to find out about RASC membership and RASC publications. ASTRONOMICAL HIGHLIGHTS December 2020 Broadcast Date December 7, 2020 The Great Conjunction of Jupiter and Saturn - December 21, 2020 As the year 2020 comes to a close, the night sky is going to provide us with a rare celestial treat. If you are out for a walk on a clear December evening, cast your gaze to the southwest horizon just after sunset. In the twilight glow you will see two bright star-like objects. The brighter of the two objects is Jupiter and the dimmer object is Saturn. On December 21 just after sunset, these two worlds at first glance will appear like a single bright object near the boundary between the constellations Sagittarius and Capricornus. Every 20 years, Jupiter catches up to Saturn and passes it as seen from our perspective here on Earth. When the two largest planets in our solar system meet up in our sky, we call this a ‘great conjunction’. Some conjunctions are closer than others. The last time these two worlds were in a ‘great conjunction’ was in May 2000, but the two planets were too close to the sun (again from our viewpoint) to be observed. In fact, the last time these two planets were as close as the upcoming December 21 conjunction was on July 16, 1623. This was during the time of Galileo, and Isaac Newton was not even born yet. But again, the two planets were too close to the sun to be observed. The last time a ‘great conjunction’ that was as close (less than 0.1 degree apart or 1/5 the diameter of the moon) and as easy to see as this year’s conjunction was on March 4, 1226. That is nearly 800 years ago during the medieval times! Please note: there was a ‘great conjunction’ in February 1961 that was 0.14 degrees apart. Close, but not as close as December 21, 2020. Although the ‘great conjunction’ occurs on December 21, start observing Jupiter catching up to Saturn from early December and onwards. This is a wonderful opportunity to observe planetary motion. On the evening of December 16, a thin waxing crescent moon will join the two planets. Enjoy a rare celestial treat as Jupiter catches up to Saturn. Photo taken on November 25. Photo Credit: Don Hladiuk Unfortunately for Canadians, the exact time of the ‘great conjunction’ is around 13:00 Universal Time or 6 am MST on December 21 (when the two planets are below the horizon). Although we are not ideally placed to see the closest part of this conjunction, this will still be an impressive sight. In fact, according to the RASC Observer’s Handbook, the two planets will be within one degree (two lunar diameters) from December 12-29. The further south you are in Alberta, the higher in the sky this conjunction will appear. It is recommended to use binoculars (e.g. 10x50) or a telescope with low magnification (40x) to observe this ‘great conjunction’. If you want to photograph this rare event, use a telephoto lens (200mm or greater) on a tripod to steady your camera. Jupiter is brighter than Saturn so you may have to overexpose Jupiter to clearly capture Saturn. Using a higher ISO setting will allow you to use a faster shutter speed to reduce any trailing due to the Earth’s rotation. If your camera has an HDR setting, turn it on, this may help to increase the dynamic range and show more detail. If you are good with Photoshop, you can take multiple images at different exposures and stack them to show more detail on the two planets. Possible Biblical Connection When I worked in a planetarium, every December we offered the Christmas Star show. In this program, astronomers looked at a possible astronomical explanation for the star of Bethlehem. I distinctly remember the list of potential candidates mentioned in the program. A bright comet, a supernova, a bright fireball but none of these astronomical events could be supported with historical observational data (the Chinese kept detailed records of sky events and would have surely noted a new star or bright comet). If you think about the roots of astronomy, most of the early astronomers practiced astrology and looked for signs in the sky. In the year 7 B.C.E. there were 3 ‘great conjunctions’ between Jupiter and Saturn in the constellation Pisces. Pisces is associated with the Jewish culture in astrology, so when Jupiter and Saturn passed very close to each other three times during the span of several months in 7 B.C.E. it was a notable event. Pisces, as well as Saturn, was the sign of the promised Messiah. Furthermore, in the Hebrew culture, Jupiter is considered to be a royal symbol, and Saturn to be Israel’s protector. Adding to the significance was that the triple conjunction in Pisces happens about once every 900 years. The first conjunction of the 7 B.C.E triple conjunction occurred in late May when the wise men may have started their journey. The second conjunction occurred in late September when they were visiting King Herod and the third conjunction appeared in the south towards Bethlehem in early December after Herod had sent them on their way. The main drawback for this explanation is that the planets during these three conjunctions were never close enough to look like a single star. But this is just one explanation. If you would like to learn more about possible astronomical explanations for the Christmas Star, there is a free public lecture offered through the Calgary Public Library entitled “The Christmas Star–An Astronomer’s Perspective”. Here is a link to register for this free lecture offered on December 14: https://www.calgarylibrary.ca/events-and-programs/programs/the-christmas-star-an-astronomers-perspective/ In summary, if you happen to miss this ‘great conjunction’ on December 21, the next one that will be equally impressive will occur on March 15, 2080. Try not to miss this once in a lifetime event. Hayabusa2 Returns to Earth A frame taken from a video of the re-entry of Hayabusa over Australia back in June 2010. Video Credit: Don Hladiuk On December 5 (Calgary time), in the remote Australian outback, a small capsule is scheduled to re-enter the Earth’s atmosphere and parachute down to a soft landing with its precious cargo. Hayabusa2 is Japan’s second asteroid sample return mission and was launched in December 2014 on a six-year mission to study asteroid Ryugu and return samples of the asteroid’s regolith to Earth for analysis. The Hayabusa2 spacecraft arrived at the asteroid in June 2018. The spacecraft deployed two rovers and a small lander onto the surface. Hayabusa2 even fired an impactor into the asteroid in February 2019 to create an artificial crater. This allowed the spacecraft to collect a second sample from beneath the surface of the asteroid from inside this fresh crater. I travelled to Australia back in June 2010 with Dr. Alan Hildebrand from the University of Calgary to observe the first Hayabusa spacecraft’s Sample Return Capsule (SRC) return to Earth. It was a spectacular sight to observe firsthand. Unfortunately, we were unable to travel to Australia this month and observe the return of Hayabusa2 due to international travel restrictions. To see my article on the 2010 event with a link to our re-entry video, go to: https://skynews.ca/following-the-falcon/ Chinese Moon Mission On December 1, China’s Chang'e-5 probe successfully landed on the near side of the moon in the moon’s Oceanus Procellarum, or Ocean of Storms, east of a volcanic plateau named Mons Rümker. This is China's third probe that has successfully made a soft landing on the moon. The Chang'e-5 probe includes a lander, ascender, orbiter, and returner. After the multi-module spacecraft entered the 200 kilometre circular orbit above the moon, the lander-and-ascender pair undocked and soft landed on the lunar surface. Over 2 days, the lander collected about two kilograms of lunar samples. The lander scooped some surface material and also drilled a two-meter-deep hole. The core sample will reveal the geologic history of the moon, with the deepest samples recording information from a billion years ago and the top samples reflecting the present day. The samples were then stored in the ascender, which lifted off from the lunar surface on December 3 and to reconnect with the orbiter and returner module. The autonomous rendezvous and docking in lunar orbit will also be a first for China. An artist’s rendition of the Chang'e 5 lander on the moon.
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