Stargazing: Astronomical computing

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton.

Astronomer Ken Tapping looks over some of the electronics at the Dominion Radio Astrophysical Observatory.

In every observatory and research centre around the world you will find copies of the Astronomical Ephemeris and American Ephemeris and Nautical Almanac.

This book, produced jointly by the U.K. and U.S., contains extensive tables of data, such as where the Sun, Moon, planets and moons of those planets, and lots of other celestial objects will be in the coming year. Today it is available in electronic form, as well as a physical book. The Observer’s Handbook, produced annually by the Royal Astronomical Society of Canada is an example aimed mainly at backyard astronomers.

The equations describing the motions of astronomical objects have been around for a long time, and don’t change much. However, producing the tables in the Ephemeris involves putting times, dates and other information into those equations and then solving them. That entails an enormous amount of meticulous and accurate calculation. Today we have electronic computers to help us. Back in the 19th and for half of the 20th Century, we had no such help, but we still needed the numbers. In those days we used computers too, but the computers were people. In fact, the original meaning of “computer,” was “a person who computes,” rather than a “machine that computes.”

Imagine a room filled with people, all with pencils and paper and mathematical tables, calculating and double-checking. Multiple people would be doing the same calculation, just to ensure that the results were correct. There were people moving among all those desks, collecting results and passing out new work. These results, after being carefully checked a few more times, were typeset and printed in that vitally important book.

Many of the desks were occupied by women. In fact, back then doing astronomical computing or being observing assistants were pretty well the only routes women could take to break into male-dominated science. This is how Henrietta Leavitt got into astronomy. She started off as a “computer,” and then worked her way into astronomical research. Leavitt went on to discover how to use Cepheids, a type of variable star, to determine the distance of far-off galaxies. The cosmic “ruler” she gave us is still the best we have for measuring the universe. Most theories for the origins and nature of the universe have the work of Henrietta Leavitt in there somewhere.

In the 1950’s digital computers started to become available for other than military work. It became possible for the U.K.’s Royal Greenwich Observatory and the U.S. Naval Observatory, responsible for producing the information in “the book,” to transfer the precision drudgery of the position calculations to non-human computers. Although such computers soon started turning up in observatories, even in the 1970’s they could not do much more than control telescopes and log data. Modern observatory computers can do the positional calculations as well. Today, smart phones contain more powerful computers than those room-filling behemoths of the 1950’s, and we can purchase or even download free software for doing our own astronomical calculations.

However, this raises a problem. There are now many programs for calculating astronomical positions, using different methods and with different accuracies. This means that for precision astronomy we still need numbers of high accuracy and consistent quality, produced using standardized methods developed over decades — the “gold standard” for astronomical calculations. Fortunately, we now manage all our tedious astronomical number crunching using machines. Also fortunately, today there are standard ways to get into science, which are open to everyone.

Venus shines brilliantly, low in the Southwest after sunset. Mars, redder and much fainter, lies to the left of Venus. Jupiter rises in the early hours. The Moon will be New on the 27th.

Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton.


Just Posted

Penticton council approves 2.9 per cent tax increase in 2020 budget

Council will vote in the new budget at an upcoming meeting in the new year

Penticton resident allegedly has rear car tires stolen

The resident woke up today to find their back tires missing and their car on blocks

Funding sought for family of 15-year-old Summerland girl with cancer

Treatment will involve two weeks in hospital, followed by eight to 10 weeks recovery at home

I’m Just Saying: Our society needs a re-sex education lesson

Jordyn Thomson is a reporter with the Western News

PIB to host new by-election after successful appeal of 2017 results

On Dec. 13, the membership voted to host a new by-election

VIDEO: More air-passenger rights go into effect this weekend

The first set of passenger rights arrived in mid-July in Canada

Best in business: North-Okanagan Shuswap companies named top 10 semi-finalists

Small businesses from Vernon, Kelowna, West Kelowna, Salmon Arm to compete for top spot

Sagmoen’s lawyer argues ‘abuse of power’ in police search

The trial of Curtis Sagmoen continued at the Vernon Law Courts on Friday

Swoop airlines adds three destinations in 2020 – Victoria, Kamloops, San Diego

Low-fair subsidiary of WestJet Airlines brings new destinations in April 2020

Aid a priority for idled Vancouver Island loggers, John Horgan says

Steelworkers, Western Forest Products returning to mediation

Navigating ‘fever phobia’: B.C. doctor gives tips on when a sick kid should get to the ER

Any temperature above 38 C is considered a fever, but not all cases warrant a trip to the hospital

Woman struck, dog killed after collision on Highway 97

Speed is not believed to be a factor and alcohol has been ruled out

Transportation Safety Board finishes work at B.C. plane crash site, investigation continues

Transport Canada provides information bulletin, family of victim releases statement

Trudeau sets 2025 deadline to remove B.C. fish farms

Foes heartened by plan to transition aquaculture found in Fisheries minister mandate letter

Most Read