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 7:37 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 May 2020 Broadcast Date May 4, 2020 A Tale of Two Comets Last month I mentioned there was a comet approaching the inner region of our solar system. The comet (called Comet ATLAS or C/2019 Y4) brightened quickly until late-March, and some astronomers anticipated that it might be visible to the naked eye in May and become one of the most spectacular comets seen in the last 20 years. The comet was discovered on December 29, 2019 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) robotic astronomical survey system based in Hawaii. This NASA-supported survey project for Planetary Defense operates two autonomous telescopes that look for Earth approaching comets and asteroids. A few days after my April column on the Calgary EyeOpener, the comet abruptly started to get dimmer instead of brighter. Astronomers speculated that the icy core may be fragmenting, or even disintegrating. ATLAS' fragmentation was confirmed by amateur astronomer Jose de Queiroz, who was able to photograph around three pieces of the comet on April 11. To obtain more data on this fragmentation event (which is relatively rare on this scale) the Hubble Space Telescope was used to take several images and astronomers were able to identify about 30 fragments on April 20, and 25 pieces on April 23. The comet fragments shown below are all enveloped in a sunlight-swept tail of cometary dust. Photo caption: This pair of Hubble Space Telescope images of comet C/2019 Y4 (ATLAS), taken on April 20 and April 23, 2020, provide the sharpest views yet of the breakup of the solid nucleus of the comet. Hubble's eagle-eye view identifies as many as 30 separate fragments. CREDITS: NASA, ESA, STScI, and D. Jewitt (UCLA) Hubble’s images support the idea that comet fragmentation is actually fairly common. It might even be the dominant mechanism by which the solid, icy nuclei of comets die. Because this happens quickly and unpredictably, astronomers remain largely uncertain about the cause of fragmentation. Hubble's crisp images may yield new clues to the breakup. Hubble distinguishes pieces as small as the size of a house. Before the breakup, the entire nucleus may have been no more than the length of two football fields. One idea is that the original nucleus spun itself into pieces because of the jet action of outgassing from sublimating ices. Because such venting is probably not evenly dispersed across the comet, it enhances the breakup. The disintegrating comet was approximately 146 million kilometers from Earth when the latest Hubble observations were taken. If any of it survives, the comet will make its closest approach to Earth on May 23 at a distance of about 116 million kilometers, and eight days later it will skirt past the Sun at 40 million kilometers. A new second comet… As Comet ATLAS was fragmenting, another comet was discovered and it too has the potential to become a naked-eye object. Newly discovered Comet SWAN has already developed an impressive tail. The comet came in from the outer Solar System and has just passed inside the orbit of the Earth. Officially designated C/2020 F8 (SWAN), this outgassing interplanetary iceberg will be closest to Earth on May 13, and closest to the Sun on May 27. The comet was first noticed in late March by an astronomy enthusiast looking through images taken by NASA's Sun-orbiting SOHO spacecraft, and is named for this spacecraft's Solar Wind Anisotropies (SWAN) camera. Although the brightness of comets are notoriously hard to predict, some models have Comet SWAN becoming bright enough to see with the unaided eye from mid May and into June. Binoculars will greatly assist your observations of Comet SWAN as it moves higher in our sky. Search low in the northeast sky around May 21. But like Comet ATLAS, there are no guarantees that Comet SWAN will continue to brighten and put on a good show in the predawn northeastern sky around 4:00-4:30 am MDT. If you would like to observe the recently discovered Comet Swan, go to this link to download or print star finder charts: https://theskylive.com/c2020f8-info One of my favourite websites called Astronomy Picture of the Day (or APOD) published a stunning photo of Comet SWAN taken by Gerald Rehmann in Namibia. To see this image go to: https://apod.nasa.gov/apod/ap200429.html Starlink Update At the Astro2020 Presentation (April 27, 2020), Elon Musk revealed a conceptual rendition of the new VisorSat design. CREDIT: SpaceX In one of my columns earlier this year I described SpaceX’s Starlink project. Starlink is a network or constellation of low earth orbiting satellites that will deliver high speed broadband internet to locations where access has been unreliable, expensive or completely unavailable. In order for this network to work at its full potential, SpaceX will have to launch approximately 4400 Starlink satellites. There are already over 400 of these satellites in orbit and astronomers are not happy about it (to put it mildly). Starlink satellites are roughly the size of a refrigerator door and have been reflecting more sunlight back to the ground than anticipated. This will make astronomy extremely difficult when the sky is literally full of these Starlinks passing through the sky. Elon Musk (CEO of SpaceX) has announced he has an idea on how to reduce the reflectivity of his Starlink satellites by using what looks like a sun visor one uses in a car. He tweeted the following: “It’s made of a special dark foam that’s extremely radio transparent, so as not to affect the phased array antennas. Looks a lot like a car sun visor.” The next batch of 60 Starlink satellites are currently scheduled to be launched later in May and this batch is equipped with the sun visors. Astronomers all over the world will be waiting to see if the satellites with the sun visors will actually be invisible to the eye after they reach their operating altitude and orientation. First Astronauts to Launch from US Soil Since July 2011 If all goes as planned, on May 27, two astronauts will launch from US soil for the first time since the last shuttle was launched in July 2011. This will also be the first time astronauts will be flying to the International Space Station onboard a commercially built spacecraft. NASA astronauts Bob Behnken, left, and Doug Hurley, wearing SpaceX spacesuits, walk through the Crew Access Arm connecting the launch tower to the SpaceX Crew Dragon spacecraft during a dress rehearsal at NASA’s Kennedy Space Center in Florida on Jan. 17, 2020. Credits: SpaceX Following the proposed May 27th launch, Behnken and Hurley are scheduled to arrive at the space station May 28 to join Expedition 63 commander Chris Cassidy of NASA and flight engineers Anatoly Ivanishin and Ivan Vagner of the Russian space agency Roscosmos. Behnken will be the joint operations commander for the Demo-2 mission, responsible for activities such as rendezvous, docking and undocking, as well as Demo-2 activities while the spacecraft is docked to the space station. Hurley will be the spacecraft commander for Demo-2, responsible for activities such as launch, landing and recovery. Selected as an astronaut in 2000, Hurley has completed two spaceflights. Pending the successful Demo-2 test, SpaceX will launch the Crew Dragon capsule on its first operational flight to the ISS later this year. The crew for this mission will be Michael Hopkins, Victor Glover Jr., Shannon Walker as well as Soichi Noguchi of the Japan Aerospace Exploration Agency (JAXA), for a six-month expedition aboard the unique space laboratory. If the launch goes as planned on May 27, one should be able to see both the ISS and the Crew Dragon capsule low in the southwest after sunset. Check Heavens-Above.com for the latest times. “What’s Up” in the May Sky Planets The brightest planet, Venus, will be visible in the western sky after sunset. Venus will be steadily dropping lower in our sky during the month of May. Venus displays phases like the moon and May is a good time to use binoculars or a telescope to see this crescent phase. A thin waxing crescent moon will be near Venus on May 24 and will be best seen shortly after sunset low in the west northwest. The Red Planet, Mars, moves into the constellation Aquarius and will be near the waning crescent moon on May 14-15 before sunrise. The two largest planets in our solar system, Jupiter and Saturn are situated low in the south eastern sky before sunrise. The waning gibbous moon will join the gas giants on the morning of May 12.