One satisfaction of astronomy is the sense of continuity with astronomers from all over the world and spanning the decades, centuries, and millennia. The wonders of the sky fill us with awe and provoke so many questions. I appreciate the multidisciplinary approach to answering these questions.
Today’s anecdote concerns an article published this week, with 25 authors from 5 countries. The Chinese Chang’e 5 probe brought back to Earth the first lunar samples in 4 decades. They targeted a place on the Moon that was suspected of being young, due to the region’s low density of craters. Galileo observed craters on the moon 400 years ago, but it was only in the 1960s that meteor impacts were confirmed to be the dominant mechanism of their origin.
The observational and theoretical development of celestial mechanics, universal gravitation, the solar nebula, and planetary accretion were all required to understand dating planetary surfaces, by measuring the size and number of craters. We also needed telescopes, rockets, robotics, petrology, geochemistry, and geochronology to complement the study. The Moon is the only planetary body where impact crater ages have been calibrated with radiometric dating, but there had been no samples so far measured that are between 3.2 and 0.8 billion years old. The new samples were dated at 1.96±.06 billion years, sitting in the middle of that gap and forcing a revision of the current crater dating method. The new date is very young for the Moon’s surface and brings up new questions, like why the Moon was still melting crust so recently.
I’m filled with a sense of connection with my fellow humans who can conceive of such questions, work on them from many different aspects over the centuries, answer some, and end up with even more questions. And I look up at the sky with happiness.
Part of the fun of amateur astronomy is getting caught up in “rabbit holes”. You see something on Facebook, that gets you looking up articles in the popular press, and then into academic publications, and they lead you in a different direction and everything is so fascinating and time just rushes by…
My current example is looking into the timing of craters on the moon – when they enter and exit the umbra or full shade of the Earth. It was an important way to figure out the time, and therefore one’s longitude, before reliable clocks were made. In the 18th century, astronomers recognized that there is a problem (La Hire, Tabulae Astronomicae, Paris 1707); the earth’s shadow is over 100 km bigger than expected. The anomaly is bigger than can be explained easily with the atmosphere. One would think this is a simple geometric problem that is fully understood, but it is still under study!
Amateur astronomers are helping collect the necessary data. Sky and Telescope publishes predicted times for when the shadow is expected to cross 24 prominent craters, and they request people to email in their observed times. Upcoming May 26, 2021, eclipse online info. Up to 2011, their database includes 22,539 observations by 764 different people. If the sky is clear between 02:52 and 05:48 on Wednesday May 26, I hope to add my name to the list!
The point is, we are a community of interesting and interested people. We set challenges for ourselves. Some are simple; some are very difficult. Get your telescope to track better. Process an image to show more detail. Understand black holes a bit more. Learn another myth of a constellation. And then we get together (virtually, these days) and support each other in these pursuits.
July 20th marks the 50th Anniversary of the Apollo 11 Moon Landing. Due to media attention a desire to take a closer look at the Moon may grow as this date approaches. Unfortunately the Moon will not rise until 11:14PM on the anniversary of the landing. As a result the International Astronomical Union is organizing a global lunar observing event on July 12th called “On the Moon Again”. Between 8PM and 11PM on Friday July 12th, members of the Victoria Centre of RASC will set up telescopes in Oak Bay at the Cattle Point Dark Sky Urban Star Park. If weather permits they will be happy to share views of the Moon with you.
Victoria Centre telescopes will also be in position at the Dominion Astrophysical Observatory every Saturday evening in July from 7:15PM to 10:45PM for weekly Star Parties. These events, co-hosted with The Friends of the DAO, will include the following Moon related lectures:
July 6th: The Voyages of Apollo by Dr. Philip Stooke July 13th: “Explore the Moon: My 50-Year, 30-Year, and 1-Year Projects” by Randy Enkin July 20th: The Apollo Moon Walk by Dr. Chris Gainor July 27th: Through the Knowledge Network: Space Suite Apollo and Space Suite IV
In addition to the above programs these Star Parties also include tours of the historic Plaskett Telescope, the Centre of the Universe Museum and Planetarium shows. Obtain free tickets to the Saturday Star Parties at the Dominion Astrophysical Observatory.
During the week of the July 20th the Friends of the DAO will hold the following additional lectures on Apollo at the Dominion Astrophysical Observatory, starting shortly after 7:00 PM.:
Tuesday July 16: Canada’s Contributions to Apollo by Dr. Chris Gainor
Wednesday July 17: Apollo in the Age of Aquarius by Dr. Dennis Crabtree
Thursday July 18: The Voyages of Apollo by Dr. Philip Stooke
The Centre of the Universe at the DAO will also be open to the public from 10 AM to 3 PM on Tuesday July 16 through Friday July 19.
Here is more detailed information of the scheduled Saturday Star Party lectures at the DAO:
July 6th 2019 – 8:30pm repeats at 9:30pm The Voyages of Apollo Dr. Philip Stooke
Abstract: A summary of the Apollo Program including its origins, steps along the way to the Moon, the choice of landing sites and a pictorial look at each mission.
Bio: Phil Stooke is a planetary scientist and cartographer with a PhD from UVic. He taught in the Centre for Planetary Science and Exploration at Western University in London, Ontario until his recent retirement. He has published The International Atlas of Lunar Exploration and similar books on Mars, and is currently revising his lunar atlas.
July 13th 2019 – 8:30pm repeats at 9:30pm “Explore the Moon: My 50-Year, 30-Year, and 1-Year Projects” Randy Enkin
Abstract: In 1969, at age 8, the Apollo missions motivated me to become an astronomer. Very quickly I mastered the subject, but then over the following 50 years I mostly found out how little I know. In this presentation, I will present my 30-year time series of lunar phase observations, and my lunar sketches from the past year which earned me the Royal Astronomical Society of Canada “Explore the Moon Observing Certificate” (https://www.rasc.ca/observing/explore-the-moon-observing-certificate). And you will be introduced to “Enkin’s Daily Moon” where images of the moon explore “the passage of time, illumination, the feminine, and world unity”. (https://www.facebook.com/EnkinsDailyMoon/)
Bio: Randy Enkin did not become a professional astronomer. He is a Research Scientist at the Geological Survey of Canada, working on earthquakes. He is an enthusiastic member of the Victoria Centre of the Royal Astronomical Society of Canada.
July 20th 2019 – 7:45pm to 10:45pm The Apollo 11 Moonwalk with Dr. Chris Gainor
Abstract: This presentation will show the entire Apollo 11 moonwalk as it was televised on the evening of July 20, 1969, along with descriptive slides. Chris Gainor will discuss the flight of Apollo 11, the symbolic aspects of the first walk on another celestial body, and the scientific work carried out by astronauts Neil Armstrong and Buzz Aldrin on the lunar surface. The presentation will begin shortly before 8 p.m., just as it did in real time in 1969, and will continue for the two hours and 40 minutes of this historic event.
Bio: Chris Gainor is a historian specializing in the history of space flight and aeronautics. He has five published books and is currently writing a history of the Hubble Space Telescope for NASA. He is President of the Royal Astronomical Society of Canada.
July 27th 2019 – 8:30pm to 10:45pm Through the Knowledge Network: Space Suite IV and Space Suite Apollo
Producers – Imagine Create Media Space Suite IV A series of 10 short films that explore the infinite wonders of our universe and our interactions with the cosmos. Space Suite Apollo Trace the history of NASA’s Lunar missions from Mercury to Gemini, to the Apollo Missions that ultimately landed a man on the moon. Set to the music of Johann Sebastian Bach, Space Suite Apollo gives viewers an unflinching look at the raw footage that continues to capture the world’s imagination.
On Wednesday, January 31st, weather willing, we will be able to view a total eclipse of the Moon. The Moon will move into full eclipse in the early hours of the morning and will be in partial phase in the western sky as the Sun rises. The Total Lunar Eclipse will develop over the course of about 3 hours. It’s a perfect opportunity to capture some snapshots of the event. Read further to find out what happens during the eclipse and how to capture it photographically.
E C L I P S E T I M E L I N E
Moon below the horizon
Moon’s eastern limb enters the penumbra
2:51 am PST
Partial eclipse begins – 1st Contact
Moon’s eastern limb enters the umbra
3:48 am PST
Total eclipse starts – 2nd Contact
Moon entirely in the umbra; deep orange red
4:52 am PST
5:30 am PST
Total eclipse ends – 3rd Contact
6:08 am PST
Partial eclipse ends – 4th Contact
Moon’s western limb leaves the umbra
7:11 am PST
7:48 am PST – approximate
Moon leaves the penumbra
8:09 am PST
A total lunar eclipse occurs when the Earth comes between the Sun and the Moon. During a lunar eclipse the Moon’s position traverses the Earth’s shadow. The Moon’s first contact with the Earth’s shadow is at the outer band of the shadow called the penumbra. The light falling on the Moon is progressively blocked until at the moment of total eclipse the Moon is completely in the darkest central area of the Earth’s shadow called the umbra. At the point of total eclipse the process starts to reverse itself until the Moon is totally out of the Earth’s shadow.
limb – the outer edge of the Moon
penumbra – the outer band of the Earth’s shadow
umbra – the darker central area of the Earth’s shadow
partial eclipse – the Moon is positioned within the penumbra
total eclipse – the Moon is positioned totally within the umbra
Above Eclipse times are for Pacific Standard Time (PST) for the west coast of North America, and are calculated from UT as presented in the Observers Handbook 2018, pages 126-27.
What do you need?
Everything from your eyes, binoculars and telescope are suitable. Bear in mind this is a long process and at this time of year dress warmly and bring a chair if you want to be comfortable.
Find yourself a location that has a clear horizon view of the west especially if you wish to view during the late stages.
Keep a log of what you see and note the time. Pay attention to how much of the light on the moon is obscured and if there are any colouration changes. During the total eclipse the Moon will take on a deep orange-red colour. The colour of the Moon is a function of contaminants in the atmosphere and varies from year to year.
Any camera with the capability of setting shutter speeds and aperture settings manually will do fine. The ability to use interchangeable lenses will be an advantage for more detailed images of the Moon. For the darker parts of the eclipse, eg. totality you should use a tripod support for best results. If you have access to a telescope you can try capturing the event using prime focus techniques through the telescope optics.
Today’s digital cameras are very sensitive to light reflected by the Moon. Use ISO 400 to ISO 800 and a long telephoto lens or zoom setting. Smartphones and point-and-shoot digital cameras will not produce rewarding photos of the eclipsed Moon, but can be useful for taking panoramic shots of your surroundings which include the eclipsed Moon.
The simplest eclipse pictures can be taken with manual settings on your camera and a normal lens, preferably supported by a tripod. For best results use a cable release to minimize vibration. Images taken in this fashion result in a small lunar image. This is why it is preferable to use a telephoto lens to photograph the Moon. For a 35mm camera try a 200mm lens or something close to this, even better a 500mm lens or higher. You may also use teleconvertors to increase magnification, these typically come in 1.4x and 2x strengths. Their downside is they reduce the effective aperture of your optical system. A 1.4x teleconvertor will decrease your effective exposure by 1 stop, a 2x teleconvertor will decrease your effective exposure by 2 stops. Work out your effective aperture of your optical system ahead of time so you don’t have to think about it on the night of the eclipse.
Effective Focal Length
with 2x teleconvertor
with 2x teleconvertor
To achieve any higher magnification than what is stated above you will have to use a telescope at prime focus. For this your manual camera does need to have the capability of using interchangeable lenses. For prime focus you will use the telescope optics as your interchangeable lens. To attach your camera to your telescope you will need two things a T-adapter that fits your camera and a telescope camera adapter that fits your telescope. The telescope camera adapter is designed to fit in the focusing tube of your telescope and is threaded to accept the T-adapter of your camera. With the magnification involved with telescopic optics it is likely that you will need to use a tracking mount. Preferably the mount should be able to track at lunar speed as opposed to sidereal but if the shutter speeds chosen are shorter than 1 or 2 minutes this is not critical.
Exposure times are the next consideration. The following exposure times are based on a medium speed film and an effective aperture that would be common with a long telephoto and teleconverter combination. Exposures may vary with your equipment based on ISO speed of film used and effective aperture. The Danjon Lunar Eclipse Luminosity Scale has been included to provide better guesstimates for totality.
Exposure Times: based on ISO 400
1/250 second at f/16
1/125 second at f/16 see note 1.
2 seconds at f/16 see note 2.
*see table below
L = 4 :
8 seconds at f16
L = 3:
30 seconds at f16
L = 2:
2 minutes at f16
L = 1:
8 minutes at f16
2 seconds at f/16 see note 2.
1/125 second at f/16 see note 1.
* Danjon Lunar Eclipse Luminosity Scale
L = 1
dark eclipse; lunar surface details distinguishable only with difficultly
L = 2
deep red or rust coloured eclipse; central part of the umbra dark but outer rim relatively bright
L = 3
brick-red eclipse; usually with a brighter (frequently yellow) rim to the umbra
L = 4
very bright copper-red or orange eclipse, with a bluish, very bright umbral rim
Note 1. 1st and 4th contact times given for the partial phases are biased for the light part of the Moon. Remember you are dealing with vastly different exposures between the light and dark parts of the Moon during eclipse. The bias of about 1 stop minus avoids overexposure of the dominant bright area of the Moon.
Note 2. 2nd and 3rd contact times given for the partial phases are biased for the dark part of the Moon. The bias of about 1 stop plus is a good strategy for negative film not quite so good for slides and digital capture given they don’t tolerate overexposure well.
The exposure times are only recommendations. Remember the cardinal rule about photography … bracket. Always try exposures plus and minus your chosen exposure. This gives you a better chance at getting usable results. Let’s all hope for clear weather. If you have any questions please send email to David Lee at email@example.com.
David Lee – original image and text
Joe Carr – updated for 2018
Brenda Stuart – illustrations
by Michel Michaud, RASC Victoria Centre Observing Co-chair & Librarian
The Lunar X is a claire-obscure effect in which light and shadow creates the appearance of a letter “X” on the rim of the Blanchinus, La Caille and Purbach craters. The X is visible only for a few hours before the first quarter slightly below the lunar terminator. Near the X, the lunar V is also visible, formed by Ukert crater and several other small craters.
If you never had the chance to view the Lunar X, also known as the Werner X, there are several time this year that feature could be visible from Victoria. The time predict the beginning of the event and all in LOCAL TIME.
23 January 2018, 2042 (8:42 pm) – Tuesday evening event
23 March 2018, 2357 (11:57 pm) – Friday evening event
21 May 2018, 0002 (12:02 am) – Monday evening event
19 July 2018, 2314 (11:14 pm) – Thursday evening event
16 September 2018, 2332 (11:32 pm) – Sunday evening event
14 November 2018, 0059 (12:59 am) – Wednesday evening event