Night-Time Photography Cancelled

Unfortunately there haven’t been enough takers this year for the Night-Time Photography short course that Royal Botanical Gardens has asked me to present to go ahead. The course has been cancelled.

A stacked star-trails image captured

A stacked star-trails image captured along the shores of Lake Huron.

When I do offer this three night course, the program is all about learning to take photographs of the night sky with a digital camera. Ideal equipment includes any digital SLR and wide-angle lens, tripod, and remote or cable release. Other digital cameras may be usable, but it will depend on whether you can take complete manual control over the camera. Functions like ISO rating, shutter speed, aperture, colour temperature and focus should all be able to be controlled manually to get the most of out night-time photography.

The Burlington Waterfront in December 2013, photographed early on e morning.

The Burlington Waterfront in December 2013, photographed early one morning.

We talk a little about telescopes, and there’s a chance to try out some telescope photography, too. However, this introductory program is intended to help you take beautiful images of landscapes and the sky at night, especially those with interesting skies and night-time city-scapes. Subjects covered include basic camera operations, composition, planning for photography at night, controlling long exposures, and computer software for various functions such as stacking star trail images.

The Burlington Waterfront and Pier before dawn.

The Burlington Waterfront and Pier before dawn.

Our first evening together is usually in a classroom. The subsequent meetings are outdoors. Locations are chosen depending on the weather and class interest. Excellent opportunities for interesting night-time photos are often to be had along the edges of Hamilton Harbour (such as at La Salle Park Marina) or along the Burlington waterfront.

Consellation Oroion rising over a surbab street in Burlington, Ontario, on the evening of 2013 March 26. Betelgeuse, the brightest star in Orion, is in the middle of the frame and about 1/8th of the way down from the top.

Constellation Orion rising over a suburban street in Burlington, Ontario, on the evening of 23 March 2013. Betelgeuse, the brightest star in Orion, is in the middle of the frame and about 1/8th of the way down from the top.

 

The moon photographed early on the morning of 29 August 2013.

The moon photographed early on the morning of 29 August 2013. Yes, this one was taken with a telescope.

I hope the program will be invited once again. I’ll post updates if that happens.

Get ready for AstroCATS 2014: Canada’s Astronomy Trade Show!

The Royal Astronomical Society of Canada – Hamilton Centre is presenting the second annual Canadian Astronomy Trade Show, AstroCATS, on 3-4 May, 2014!

The web site for this exciting event is: http://www.astrocats.ca/

The big show will open at 10 AM on Saturday 3 May, and close at 6. On Sunday it opens again at 10 and closes at 4. AstroCATS 2014 will be held in the David Braley Athletic & Recreation Centre at Mohawk College, 135 Fennell Ave. West, Hamilton L9C 1E9.

Visit the web site to find lists of vendors, special speakers, and all of the exciting highlights planned for the show in May. Hope to see you there!

The Equinox is coming. So is the Equilux. So what’s the difference? About four days.

A term from astronomy that has entered common use is Equinox, which translated from its Latin roots roughly means “Equal Night.” Most people think that the Spring (or Vernal) Equinox and the Fall (or Autumnal) Equinox are the days when the length of the daylight and the length of the night are equal. Close, but not quite right.

As the days lengthen from winter toward summer, there certainly is a day during which the length of time we see sunlight and the length of time it’s dark are roughly the same. Technically, however, the timing of each Equinox is defined as the moment when the earth passes a particular point in its orbit around the sun. It’s not defined by the local length of the day.

We have extended our imaginations into space, and covered it with geometric patterns. One of those patterns is an imaginary circle that runs around the entire sky and is called the ecliptic. This is the circle that marks the apparent position of the sun throughout each year, relative to the background stars. It’s called “ecliptic” because of its importance in determining the dates of eclipses. For a lunar or a solar eclipse to take place, the sun, moon, and earth all have to be in alignment with the ecliptic.

Because much of the solar system is in a pretty flat configuration, most of what happens in the solar system also happens near the ecliptic. The orbits of the earth, Mars, Venus, Jupiter, and many other things in the solar system lie in more or less the same plane. So, when you are able to spot any of the planets you’re seeing, approximately, where the ecliptic lies in the sky.

Another similar geometric pattern or circle that is projected into the sky for practical reasons is defined by the earth’s own equator. Astronomers can plot a line across the sky which corresponds, in the “up” direction, to where the equator is on earth. If that’s a little hard to envision, just consider the North Star, Polaris. By accident it sits within a degree of the place in the sky directly above the earth’s north pole (the rotational pole, not the magnetic pole. They’re different things, for another day). From Polaris the celestial equator is 90 degrees south in all directions.

Right. So, two circles projected up in the sky (Picture an orange with two rubber bands around its middle that cross each other as viewed from the inside). They are tilted with respect to each other by the same amount as the earth’s rotation is tilted relative to the position of the sun – around 23 degrees. Each Equinox is defined as the time at which the earth passes the place where the two lines cross. At that moment, the terminator – the place where the sunlit side of the earth and the night side of the earth meet – is at right angles to the earth’s equator.

Now, you’d think that this perpendicular arrangement would mean day and night are of equal length, and geometrically it’s true. However, what we actually see is much more complicated. The apparent length of daylight and night differs from place to place on earth. One of the big factors is the bending effect of the earth’s atmosphere. We sit under an ocean of air, and one of the consequences of our atmosphere is that light is bent as it comes in from space; air acts like a huge lens. The closer an object is to the horizon (like the sun at sunset or sunrise) the more the bending is apparent. This is because the light at these low angles must pass through much more air to reach us. It acts as a thicker lens closer to the horizon.

The consequence of this bending of sunlight is that the time something actually happens in the sky is not necessarily the time we see it happening from our vantage point under the atmosphere. In fact, this bending is enough that at the horizon it’s enough to make the sun appear to be more than its own diameter “earlier” in rising than it would without the atmosphere there. A staggering thought – when we see the sun just getting up over the horizon in the morning, it’s actually still below the horizon geometrically!

The other factor is the apparent size of the sun. From the earth’s perspective the sun is about a half a degree across, compared to the whole 360 degrees of the sky. Sunrise and sunset do not happen instantaneously. Sunrise is defined as the moment that the sun’s disk just appears on the horizon for any particular morning. Sunset is defined as the moment when the last bit of the sun just disappears past the horizon from any particular location.

These two things combined are enough of an effect that the Equilux, the day that has equal hours and minutes of sun above and below the horizon, is about four days before the Vernal Equinox and about four days after the Autumnal Equinox in the area of Hamilton, Ontario. The timing of the Equilux may be different in your location. In 2013 the Spring Equilux – the date that daylight and nighttime hours are closest to being 12 and 12 – falls on 16 March. The corresponding Equinox this year takes place about 7:02 AM on 20 March.

In September 2013 the Autumnal Equinox, marking the official beginning of fall, is at 4:44 PM on the 22nd. The Fall Equilux, however, for Hamilton is on 25 September.

Sources:

  • Thanks to the on-line calendar of the Hamilton Amateur Astronomers for the Equilux and Equinox dates and times for 2013. http://amateurastronomy.org/
Copyright © David Allan Galbraith 2013

“Night-Time Photography” at RBG: An Unabashed Plug

This post is a plug for a new public program at Royal Botanical Gardens that I will be presenting in February and March. The goal of the program is to introduce participants to photographing the night sky with camera and tripod, although we will talk a little about telescopes, too.

There are many wonderful things to photograph at night. You can take a look at some of my examples here at the Pine River Observatory blog, on my page entitled “Astrophotography Gallery.” We’ll consider both celestial objects – like the moon and stars – and also landscapes at night.

The stars make arcs in the sky in long exposures. This image was composed from about 120 individual wide angle photos taken with a Nikon D7000 on a tripod.

The stars make arcs in the sky in long exposures. This image was take along the shores of Lake Huron in August, 2012. It was composed from about 120 individual wide angle photos taken with a Nikon D7000 on a tripod, using free software called StarStaX.

On the first night, in the classroom at RBG Centre in Burlington, we’ll take a look at examples of night-time photography, and go through the basics of photography at night, including the kinds of scenes likely to be encountered and the equipment that might be used. There will be a light (pardon the pun) orientation to objects in the night sky, discussions about where and when photos may be most effective, and what limits photography at night. We’ll also talk about handling photographic equipment in cold weather.

The second night will be a practical  night out shooting the sky. The date for the second night is variable and will be shifted as needed, primarily to accommodate the weather. Keep your fingers crossed for some clear nights at the beginning of March!

The third night will be “show and tell” for the participants, and examples of working with software to prepare final images. It will likely be in later March, but might also be shifted, with the permission of everyone, to accommodate fitting in appropriate outside time.

There are still a few places. You can reach the RBG’s on-line ticketing program at: http://tickets.rbg.ca/PEO/all_events.asp

To find “Night-Time Photography,” select the link entitled “For The Nature Lover” at the lower left side of the page.

This program is being offered for a fee that goes to support Royal Botanical Gardens’ important charitable objectives. I’m not getting paid for this program. Just so you know.

Royal Botanical Gardens presents "Nighttime Photography" in 2013

Royal Botanical Gardens presents “Night-Time Photography” in February and March 2013

Happy New Year! But Why January 1st?

Have you ever wondered why January 1st is the first day of the New Year?

Vintage New Years Card

Vintage Happy New Years Card Celebrates the Turn of the Year

Our present everyday calendar is pretty much taken for granted, and it works fairly well. It has 365 days in it (more or less), given the adjustment of an extra day every four years (more or less). Most people know that the two equinoxes and the two solstices (natural events) fall more or less within a day or so of the same date each year, so it must have some synchronization with celestial events.

Many people may also be aware that the present calendar used by most of the world (and there are still some others in use, by the way), is called the Gregorian Calendar, and they may even know that it’s named after Pope Gregory XIII. As readers of the Pine River Observatory blog, I hope you might already have that information! But did you know that the Gregorian calendar was created by one of the most respected astronomers and mathematicians of his day, and that one of the largest craters on the moon is named in his honour?

I’m getting ahead of myself. First, we have to consider the matter of calendars themselves, what they do, and then we can see how January became the beginning of the year we now mark.

Calendars are tools that allow people to keep track of time and plan when things are going to take place. Calendars started, and are still, astronomical tools. Although we are used to having one calendar in the west today, there are three different cyclical celestial events that are all involved: the cycle of the earth’s revolution around its polar axis (defining one day), the cycle of the moon’s orbit around the earth (defining one lunar month) and the cycle of the earth’s orbit around the sun (defining one year). Making up a calendar would be easy if these things were strongly related to each other – but they aren’t.

The earliest antecedents of today’s calendar can be traced to Italy roughly 3,000 years ago, with a calendar consisting of ten months of around 30 days each, which began each year in March. About 700 BC January and February were added to the calendar, making the Roman Calendar. About three hundred years later, January was designated as the first month of the year – and thus we have the first of January being considered as the beginning of the year – around 450 BC. Further adjustments were made up to 46 BC, but the passing of the seasons – and the “annual” cycle of the sun – still didn’t align with the calendar. Julius Caesar instigated a further refinement by the astronomer Sosigenes of Alexandria that brought things closer together. This calendar, the Julian Calendar, was aligned only to the solar year. Any attempt to synchronize the annual calendar with lunar cycles was abandoned.

For something close to 1,600 years the Julian Calendar was used by the western world. However, by then errors had accumulated to the point where the calendar date of the equinoxes had crept forward by 13 days, seriously throwing off things like the Christian celebration of Easter. Pope Gregory XIII put into motion the reformation of the calendar in 1582. A Jesuit astronomer and mathematician from Germany, Christopher Clavius (1538–1612), was the person responsible for working out the details of the new calendar. It worked much better than the Julian Calendar in matching up with the solar year’s accounting of days, and it’s the calendar we still use. However, it was not universally adopted; it was another 200 years before it was taken up in England and he United States, for example. And, there are other calendars still in use in various societies around the world, and for various purposes.

So, the convention of starting the year on the first of January has remained in place in the descendants of the Roman Calendar – including our own. Like many things, the convention of having the year start on the first of January is just that – a convention. It is the result of a long history of changes that led to a calendar that works pretty well, but it’s also a compromise.

Both Sosigenes of Alexandria and Christopher Clavius are memorialized in the names of craters on the moon.

Crater Clavius is in the southern highlands of the moon. At 230 km across (and with 18 associated smaller craters) Clavius is one of the largest craters on the moon; remembering for whom it was named is a link to the story of the calendar most of us use today, 430 years after his re-alignment of the days of the year. Crater Sosigenes (17 km across) is located along the western edge of Mare Tranquillitatis (as are three satellite craters, Sosigenes A, B and C), to the east of a larger crater named for Julius Caesar (90 km, with 10 smaller associated craters). Rimae Sosigenes, a lunar rille, stretches to the east of the crater. Apollo 11’s lunar module landed about 280 km south east of this area.

Sources

Information on the history of calendars: Kaler, J. B. 1996. The Ever-Changing Sky: A Guide to the Celestial Sphere. Cambridge University Press. Cambridge, UK. Pg 174-175.

Lunar feature names: International Astronomical Union (IAU)  Working Group for Planetary System Nomenclature (WGPSN). Gazetteer of Planetary Nomenclature. Available on line at: http://planetarynames.wr.usgs.gov/

Public domain vintage Happy New Years Card: http://webclipart.about.com/od/New_Year_Clip_Art/ss/Vintage-Happy-New-Year-Moon.htm

Looking Forward to 2013

There are always lots of things happening in astronomy. Here are some anticipated highlights for 2013.

In the Sky

On 28 April 2013 the planet Saturn will be at opposition – the closest approach that the ringed planet makes to us during the mutual orbits of earth and Saturn. Will be the best time during the year to look at Saturn with a telescope. There’s also a partial (“penumbral”) lunar eclipse on the 18th of October, which might be visible in Ontario.

Nice meteor showers show up every year, assuming that the weather cooperates. Here are some of the more prominent ones:

  • Just after New Year, on January 3-4, the Quadrantids Meteor Shower is at its peak. A dark location after midnight is recommended; find the constellation Bootes to find the expected radiant point.
  • In August, the Perseids Meteor Shower presents its peak on the 12th and the 13th. This is always a favourite meteor shower, with as many as 60 meteors per hour showing up.
  • November has the Leonids Meteor Shower, peaking on the 17th and 18th. This shower looks like it’s originating in the constellation Leo, and will be best viewed after midnight.
  • In December, weather permitting, the Geminids Meteor Shower has its peak December 13-14. Best viewing will be after midnight, in the east.

Perhaps the most anticipated sights in 2013 are two comets expected to make interesting – and possibly spectacular – shows. Comet 2014 L4 (PanSTARRS) is currently being watched by astronomers in the southern hemisphere, but by March it should reach its greatest brightness and be visible up here in the north (http://cometography.com/lcomets/2011l4.html). 2014 L4 (PanSTARRS) is predicted to peak at a magnitude near -0.5 between 8-12 March 2013 (like a very bright star). Like the vast majority of comets, it will come no where near to the earth, never getting any closer than 0.3 AU – a third of the distance from the earth to the sun. By late May it should be very high in the night sky in the north – perhaps 5 degrees from Polaris – but will be much fainter too.

Great Comet of 1680.

A German engraving of the Great Comet of 1680. Some sources are prediction that Comet C/102 S1 (ISON) will be as spectacular… but only time will tell.

Also eagerly anticipated is Comet C/2012 S1 (ISON), (http://cometography.com/lcomets/2012s1.html). It was discovered this past September and might (emphasis might) be one of the greatest comets of recent memory. It will dip very close to the sun – about 0.1 AU or one tenth of the way from the earth to the sun – and may reach its maximum brightness on 28 November 2013. While very hard to predict, the size and orbit of the comet has some astronomers predicting a magnitude (brightness) of -13 for this beast. That’s brighter than the full moon! It may also have a very long tail. As comets are best described as irregular, big dirty snowballs, just how they behave when the sun starts to heat them up and generate their tails and other features is impossible to predict with precision. I’ll post updates (as will everyone interested in the sky, I’m sure!) as they become available.

(source of 17th C. illustration: http://ksj.mit.edu/tracker/2012/10/kehouflop-redux-out-near-saturn-monster).

On the Ground

This year the Hamilton Amateur Astronomers is hosting ASTROCATS 2013: The Canadian Astronomy Telescope Show, May 25th & 26th at the Sheridan College Athletics Centre, Oakville, Ontario. Unfortunately yours truly can’t attend, but it should be a great show, with a lot of vendors representing the best in astronomy gear (come to think of it, it’s likely a GOOD THING I can’t go. The national debt couldn’t take the strain): http://astrocats.ca/.

SkyFest is the annual three-day event put on by the North York Astronomical Association. August 8-11, 2013, held at River Place Park, RR 3, Ayton, Ontario (northwest of Mount Forest). It’s Canada’s biggest star party: http://www.nyaa.ca/index.php?page=/sf13/sf.home13.