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.

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.

 

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

These nails were collected off the Campbell Mountain bike trails in Penticton this weekend. Someone placed them all over the trail. (Facebook)
Hundreds of nails placed on popular Penticton bike trail

A mountain biker took to Facebook to warn others about the nails

Chrystina Barnard, owner of Lucky’s Pet Supply, has made it her mission to visit as many patios in Penticton as a way to promote restaurants. Here she is enjoying an eggs benny with her best fur friend at Loki’s Garage in Penticton. (Facebook)
Penticton foodie commits to 19-day patio crawl to promote local restaurants

The small business owner wanted to help out eateries hurt by the new restrictions

Flight with COVID
Another Kelowna flight with COVID-19 exposure

Westjet flight on April 5 from Kelowna to Edmonton

Penticton fire truck
Residents evacuated after apartment fire in Penticton

The fire started in an apartment on Government Street Saturday night

Lori Jantz snapped this picture of a fight between a bald eagle and an osprey above Osoyoos Lake on Friday. (Lori Jantz photo)
Battle in the sky erupts above South Okanagan lake

Bald eagle and osprey fight mid-air in Osoyoos

B.C. Health Minister Adrian Dix and Premier John Horgan describe vaccine rollout at the legislature, March 29, 2021. (B.C. government)
1,262 more COVID-19 infections in B.C. Friday, 9,574 active cases

Province’s mass vaccination reaches one million people

A second case of COVID-19 has been confirmed at Vernon’s BX Elementary School. (Kerry Hutter photo)
Second COVID case confirmed at Okanagan elementary school

Exposure at Vernon’s BX Elementary happened April 6 and 7

People walk past the Olympic rings in Whistler, B.C., Friday, May 15, 2020. Whistler which is a travel destination for tourists around the world is seeing the effects of travel bans due to COVID-19. THE CANADIAN PRESS/Jonathan Hayward
Adults living, working in Whistler, B.C., eligible for COVID-19 vaccine on Monday

The move comes as the province deals with a rush of COVID-19 and variant cases in the community

RCMP crest. (Black Press Media files)
UPDATE: RCMP investigating after child, 6, dies at motel in Duncan, B.C.

The BC Coroners Service is conducting its own investigation into the circumstances around the child’s death

Highway 97 being converted to four lanes in April 1990. This photo taken in Lake Country. (Greater Vernon Museum and Archives Photo #14025)
HISTORY: How the old Highway 97 in Lake Country got new name

Pelmewash Parkway recognizes the First Nations history in Lake Country

RCMP display some of the fish seized from three suspects who pleaded guilty to violating the Fisheries Act in 2019, in this undated handout photo. THE CANADIAN PRESS/HO - RCMP
3 banned from fishing, holding licences after overfishing violations near Vancouver Island

Mounties seized the group’s 30-foot fishing vessel and all equipment on board at the time

B.C. Premier John Horgan responds to questions during a postelection news conference in Vancouver, on Sunday, October 25, 2020. British Columbia’s opposition Liberals and Greens acknowledge the COVID-19 pandemic has presented huge challenges for Horgan’s government, but they say Monday’s throne speech must outline a coherent plan for the province’s economic, health, social and environmental future. THE CANADIAN PRESS/Darryl Dyck
Horgan’s NDP to bring in throne speech in B.C., Opposition wants coherent plan

Farnworth said the budget will include details of government investment in communities and infrastructure

Most Read