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.

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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. Photo Credit: CNSA

When close to Earth, the returner will separate from the orbiter and carry the samples back to Earth, which will finally land in North China's Inner Mongolia. China has not provided any specific dates but the samples are expected to return to Earth in early December

What’s Up in the December Sky

Planets

Jupiter catches up to Saturn this month Saturn and Jupiter appear as one star-like object low in the SW just after sunset on December 21 Mars shines brilliantly in the southern sky after sunset Venus is the bright star-like object located low in the east-southeast before sunrise

Artificial Satellites

The International Space Station (ISS) will be visible over Alberta in the evening sky for the first two weeks of December. It reappears in the morning sky around December 20. Look for a bright, slow moving star-like object generally moving in a west to east direction. For future dates and times for ISS passes over Alberta, go to this website and enter your location (important to change your location from the default): https://heavens-above.com/

Another website for ISS passes is operated by NASA: https://spotthestation.nasa.gov/sightings/index.cfm

Meteor Shower

The Geminid meteor shower is active between December 7 and 17 and peaks on December 13/14, with typical hourly meteor rates around 80 meteors per hour under ideal dark sky conditions. The Geminids’ orbit in our solar system intersects Earth's orbit near the side directly opposite the Sun. This shower is one of the few that offers a good chance of seeing meteors before midnight. The parent body of the Geminids is a curious object designated 3200 Phaethon. What makes Phaethon interesting is that it appears to be an asteroid instead of a comet. Planetary scientists suggest that many of the asteroids whose orbits that cross Earth's orbit may in fact be old comets. This year the moon will not interfere with this annual display.

Dates to Remember

Dec 05: JAXA’s asteroid sample return mission is scheduled to land in central Australia with its precious cargo Dec 06: SpaceX to launch a cargo Dragon to the ISS Dec 11: A Zoom presentation by Don Hladiuk on Chasing Shooting Stars and Moon Shadows. Here is a link for this free presentation: https://sunshinecoastastronomy.wordpress.com/ Dec 12: A thin sliver of the moon will occult (or eclipse) Venus (during daylight hours around 2pm MST) Dec 13/14: Geminid meteor shower peaks (see above) Dec 14: Free Public Lecture on The Christmas Star–An Astronomer’s Perspective. Register at the Calgary Public Library: https://www.calgarylibrary.ca/events-and-programs/programs/the-christmas-star-an-astronomers-perspective/ Dec 14: A Total Solar Eclipse of the Sun seen from Pacific & South America (not visible from North America) Dec 15: China’s lunar sample return mission will return to Earth around this time Dec 16: A thin waxing crescent moon will be near Jupiter and Saturn low in the southwest sky shortly after sunset Dec 21: Winter Solstice. At 3:02 am MST the Sun will reach its most southerly point below the ecliptic. Shortest day. Dec 21: Great Conjunction with Jupiter and Saturn. Last one was in the year 2000. See above. Dec 23: Waxing gibbous moon near Mars in the evening sky

Follow Don on Twitter at: https://twitter.com/astrogeo

For more astronomy info go to: The Calgary RASC website

December 2020 Sky Chart Set for December 15 – 18:00 MST

Sky Chart courtesy of Heavens-Above.com

NB. Jupiter and Saturn are too close together to be displayed as separate dots.

Don will be back in January 2021.

Previous Astronomical Highlights:

• November 2020 • October 2020 • September 2020 • August 2020 • July_2020 • June_2020 • May 2020 • April 2020 • March 2020 • February 2020 • January 2020 • December 2019

Other Sources of Current Sky Information:

• Monthly Star Charts for the Calgary Area • Calgary RASC Monthly Events Calendar • Calgary Weather - from Environment Canada • Heavens-Above Main Page (for Calgary) - ISS passes, Iridium Flares and Satellites visible from Calgary • Dark Sky - generate a monthly calendar of Moon phases, Sunset/Sunrise, Moonset/Moonrise, hours of darkness etc. • Sky News - the Canadian astronomy magazine. • Astronomy Magazine • Sky and Telescope Magazine • Skymaps.com - download and print a monthly Evening Sky Map and Calendar • Astronomy Picture of the Day • Comets currently visible • SkyHound - Current Observing Information • NASA JPL Space Calendar