The (Northern) Summer Solstice, today at 2:44 PM PDT, marks the earliest beginning of summer since 1896.
Solstice dates in Vancouver classified by “type” (the remainder after dividing the year by 4). Years evenly divisible by 4 (type 0 – such as 2016, 2020, 2024) can have early solstices.
The chart above shows how the quadrennial correction (which the Julian Calendar is solely based on) works well short term, but over a longer period of time (130 years or so), it produces a significant error (one full day). To correct this, the Gregorian Calendar introduces another correction which is to omit leap days in some of the years that centuries begin with (or end, some would say). Years like 1700, 1800, 1900, 2100, 2200, 2300 etc. are chosen for this correction. So, we are in a deep stretch without this centennial correction and the seasons’ start dates will be falling even earlier until late 21st century.
Our observing director, Robert Conrad, wrote this post on facebook about comet C/2017 T2 (PANSTARRS).
“Don’t miss the opportunity on the night of June 15th to see comet C/2017 T2 (PANSTARRS) in the same FOV as the bright galaxy Messier 109 and the bright star Gamma Ursa Majoris. View it around 11:00pm when it’s dark and still relatively high in the sky. Good luck! “
The good news is that the comet is still close to M109 on the night of Tuesday June 16th, 2020 and the skies are forecasted to be somewhat clear in Vancouver. It is easy to find in the North-Western skies because of its proximity to Phecda – a bright star in the bowl of the Big Dipper. Recent observations have the comet at magnitude 8.5 so it is visible in small telescopes.
Galaxy M109 next to the Bowl of the Big Dipper at 11:00 pm PDT on June 16th, 2020 from Vancouver
Comet C/2017 T2 (PANSTARRS) is within 1° of Galaxy M109
Join us for our “GA Lite” series of astronomy webinars, a great follow-up to the RASC Virtual General Assembly. The series is scheduled over the two weekends June 13&14 and June 20&21, with more details at
Long-time RASC Vancouver member, Barry Shanko, received the President’s Award as announced at the 2020 RASC AGM this afternoon. A hand out of the 2020 RASC awards winners is available but information about the President’s Award is available in the following excerpt.
President’s Award
This award is given at the President’s discretion, usually once a year, to a member (or members) who has/have made an important contribution to the Society.
Mr. Shanko served as speaker coordinator for the Vancouver Centre for 31 years and was active in RASC public outreach efforts in the Vancouver area. In his life he had to overcome many economic and health challenges but became known for his ability to attract outstanding speakers from around Canada and the U.S. for Vancouver Centre events. Unfortunately, Mr. Shanko passed away unexpectedly just before his 60th birthday on 2020 May 2.
The Board of Directors of the Royal Astronomical Society of Canada met recently, and unanimously approved the following statement:
In response to recent events, The Royal Astronomical Society of Canada wishes to state that it supports peaceful protests and dialogue across the world aimed at addressing longstanding issues of racial inequality, and in particular anti-Black discrimination and violence. The Society is dedicated to equality of opportunity and treatment for all, regardless of race, sex, gender identity or expression, sexual orientation, national or ethnic origin, religion or religious belief, age, marital status, and disabilities. We are opposed to all forms of unlawful and unfair discrimination.
In two days (June 3rd, 2020), our twin sister planet will pass between us and the Sun. This brings fond memories of the similar passes in June 2004 and June 2012, which both resulted in transits across the solar disk, but this time around, Venus will just miss the solar disk by a quarter of a degree on its passage from northern to southern ecliptic latitudes.
Conjunction of Venus with the Sun on June 3rd, 2020, courtesy of Sky Safari
This 8 year cycle of Venus was known even to ancient Mayas. In 8 Earths years, Venus will make 13 orbits around the Sun and since both planets orbit the sun in the same direction, there will be 13 – 8 = 5 synodic periods of Venus looking from planet Earth. Any Fibonacci fans out there?
During 5 synodic periods Venus will go through 5 inferior conjunctions. Only one of these five is close to the Sun in the current epoque, two will be midway to the maximum distance which is just under 9 degrees and the remaining two will be very close to the maximum angular distance from the Sun.
5 synodic periods of Venus actually falls short of 8 years by 2 and a half days. With this, all inferior conjunctions will slowly move earlier in the year within each series. The 2020 conjunction, happening on June 3rd, is part of the June-May series, as was the 2004 transit, which occurred on June 8th and the 2012 transit, which occurred on June 5th.
With this years conjunction being a near miss, the question becomes: when will Venus next be so close to the solar disk? The visualisation below shows about 130 years of inferior conjunctions and each of the five seasons is labelled by the pair of months that it occurs in during the 21st century.
130 Years of Inferior Conjunction of Venus with the Sun, courtesy of Milan B. and Tableau
As the Jun-May series conjunctions (the green series above) are slowly moving away from the Sun and will not result in any transits for many centuries, we will need to turn to another series to bring us the next sequence of close passes and transits. The Jan-Dec series conjunctions, which are currently far from the solar disk are slowly inching (in astronomical terms) towards the Sun and also regressing from mid January (in early 2000’s) into early December (in the early 2100’s) which will result in another pair of transits, this time the December transits of 2117 and 2125.
Venus one week after the 2015 Inferior Conjunction, Aug 22nd 2015, courtesy of Milan B. and SkyWatcher.
From the chart above it becomes apparent that after the June 2020 conjunction, Venus will not venture so close to the Sun (from Earths perspective) for another 97 years, until the 2117 transit. Hopefully, some of the younger generations will get a chance to see this remarkable astronomical event.
Frank Drake is 90 years old today (May 28, 2020), making it a good day to ponder the odds for extraterrestrial life. Drake, an astrophysicist, has been involved in the search for extraterrestrial intelligence, including the founding of SETI, for decades. One of his best-known contributions was the development of the Drake Equation in 1961. The equation was originally intended to promote discussion between Drake and his colleagues on extraterrestrial life. The equation is still alive and relevant today with new revisions being proposed, debates on the values for its parameters, and a continuing appreciation of it from the general public. On the occasion of Frank Drake’s birthday, here is the Drake Equation plus two others inspired by it.
The Drake Equation estimates the number of communicating civilizations in the cosmos or more simply, the odds of finding intelligent life. The equation calculates the number of communicating civilizations by multiplying together estimates of several parameters. SETI’s web page displays the Drake equation as:
Where
N = The number of civilizations in the Milky Way Galaxy whose electromagnetic emissions are detectable.
R* = The rate of formation of stars suitable for the development of intelligent life.
fp = The fraction of those stars with planetary systems.
ne = The number of planets, per solar system, with an environment suitable for life.
fl = The fraction of suitable planets on which life actually appears.
fi = The fraction of life-bearing planets on which intelligent life emerges.
fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = The length of time such civilizations release detectable signals into space.
R=7, fp= 90%, ne= 0.3, fl =10%, fi = 1.0%, fc = 1.0%, L = 10,000,000
which yields N = 189 civilizations in our galaxy.
The Drake Equation provides an estimate of the number of civilizations whose electromagnetic emissions are detectable. Astronomer Sara Seager proposed an equation that based on detecting planets whose biosignature gases can be detected. Biosignature gases, produced by living organisms, accumulate in a planet’s atmosphere to levels that can be detected with a remote space telescope. The Seager equation is:
N = N* FQ FHZ FO FL FS
Where
N = the number of planets with detectable biosignature gases
N* = number of M stars with I < 13
FQ = fraction of quiet M stars
FHZ = fraction with rocky planets in the HZ
FO = fraction of observable=transiting systems observable with JWST
FL = fraction with life
FS = fraction with detectable spectroscopic signatures
Seager’s estimates for these parameters for M stars in the TESS/JWST survey are
Sara Seager posted a YouTube video honouring Drake and the influence he had on her own research.
A form of Drake’s equation was used by Gene Roddenberry to pitch Star Trek in 1964. Roddenberry was trying to justify the large number of inhabited planets in the show. He did not have a copy of the equation so he made up his own variant
with no explanation of the parameters. It is said that Frank Drake later pointed out to Roddenberry that a value raised to the first power is merely the value itself when he visited the Star Trek set.
Happy 90th Birthday to Frank Drake, a pioneer in the search for life elsewhere in the universe.
I found it interesting to compare images of two Pinwheel galaxies despite the difference in targets and imaging setups.
The Pinwheel Galaxy, M101 in Messier’s catalogue, is a beautiful face-on spiral galaxy that is popular with astrophotographers. Tonight at 11:00 pm from Vancouver, it is at an altitude of 84°- almost straight up – in the constellation Ursa Major. This is a great location for visual observing or imaging to minimize atmospheric disturbance. I collected image data of M101 in 2014 with a small 100 mm refractor.
Another pinwheel from Messier’s catalogue is M83, also known as the Southern Pinwheel. It is visible at the same time but its altitude is just 10° above the southern horizon in the constellation Hydra when viewed from Vancouver. That location makes M83 a difficult target so I decided to use a remote telescope in Chile at latitude 30°S. From Chile, M83 reaches 89° when transiting the meridian at 02:16 am UTC.
M101 – The Pinwheel Galaxy from Coquitlam, BC, Feb 2014
M83 – The Southern Pinwheel from Chile, May 2020
Click on the image to open a larger view.
Two very different setups were used to collect the imaging data. The M101 data was collected using my own equipment from Coquitlam, BC:
Skywatcher 100ED pro refractor
Nikon D5100 DSLR
Total Exposure: 30 min with 20 subframes at 90 sec and ISO 1600
Heavy light pollution (sqm: 18.5, Bortle class 7)
The M83 data was from the Telescope.live remote CH-1 telescope in Chile:
Planewave CDK24 (60 cm, F6.5)
FLI ProLine PL900 (3056 x 3056)
Total Exposure: 90 min with 9 Luminance and 3 each of Red, Green, Blue subframes at 300 sec and 1 x binning.
Pristine Dark skies at an elevation of 1500 m (sqm: 21.8, Bortle class 1) – same skies as the Gemini South telescope.
So it is not at all surprising that the M83 image is better with 6X more aperture and 3X longer exposure.
The two galaxies are both face-on spirals, appear somewhat similar, and are close to the same visual magnitude but some of their physical properties are quite different as shown in the table below.
M101
M83
Constellation
Ursa Major
Hydra
Visual magnitude
7.86
7.54
Angular Size
28′.8 × 26′.9
12′.9 × 11′.5
Distance
1.8 Mly
14.7 Mly
Diameter
170,000 ly
55,000 ly
Radial velocity
241 ± 2 km/s
508 km/s
Number of Supernovae
4
6
M83 has spawned a large number of supernova explosions — six in total that we have observed (SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968L, and SN 1983N). Only 4 supernovae have been observed in M101 but SN 2011fe, a Type Ia supernova, reached magnitude 9.9 in 2011 and was visible in binoculars.
M83 is thought to have a double nucleus at its core. The paper “Double nucleus in M83” provides evidence of a second hidden nucleus that is more massive than the visible nucleus.
