STARGAZING: A cosmic telescope

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

It is not clear exactly when glass was invented, although it was probably by accident, when someone lit a particularly hot fire on sand.

It was certainly a long time ago. It is also not clear when one of our ancestors, when playing with a piece of glass that happened to be thicker in the middle and thinner at the edges found he or she could catch the sunlight and burn themselves or their friends, or set fire to things. Those early experimenters put us on the road to modern telescopes, cameras and other optical equipment. These early lenses and their modern, more precise descendants all make use of an important fact; light travels more slowly in glass than it does in air.

This principle is what gives us modern telescopes and other optical equipment. Imagine a long line of skaters, with their arms linked, skating in a long line abreast. If we slow down the skater in the middle, and the ones either side a little less so, and the others by decreasing amounts as we get further from the middle of the line, that line will become a curve. That curve will get smaller and tighter until all the skaters end up in a heap.

We have collected all the skaters and brought them together at one point. In the same way we can use lenses and mirrors to collect and concentrate light. This is instrumental in astronomy, because most cosmic objects are very faint. This is why so much of our efforts in telescope development goes into making bigger and bigger light collectors. The biggest currently in our plans will have a light collector thirty metres in diameter. However, there is a way we can achieve a far bigger light collector. How about one that is bigger than a galaxy? It sounds incredible, but this is something that is now a standard research tool.

We have achieved that thanks to Albert Einstein and the other physicists who have analyzed the properties of space and time. They showed us that large, massive objects, like a planet, star or galaxy, distort space, rather like the way a big, iron ball dropped in the middle of a rubber sheet would pull it downwards into a depression. Now imagine a skating rink with such a depression in the middle. Once again we have our line of skaters, holding hands, all resolutely skating at the same speed. The skaters who encounter the hole will have further to travel than those who donít, because they have to go down one side and up the other. The skater going through the bottom of the hole will be most affected, and others less so. The result will be the skaters who met the hole will lag behind the others, and the line will be pulled into a curve, and once more the skaters will all end up in a heap. That hole is acting like a lens.

The distortion of space by a massive galaxy affects light the same way as the hole affected the skaters. It bends light, bringing it together at one point; it is focussed. We call this process gravitational lensing. The galaxy acts as an enormous light collector, concentrating the light of very faint objects lying beyond. Without that concentration of their light we would never be able to see them. Of course we can only do this when there is a large galaxy conveniently located in the direction we want to look, and these gravitational lenses are not perfect, so it sometimes requires a lot of image processing to make sense of what we are seeing. However, without the process we would not be seeing anything; it would be too faint.

Such cosmic telescopes will never replace good ground and space-based telescopes.  However, they provide a valuable complement to those instruments in addressing important questions about the early history of the universe and that time long ago and far away, when the first stars and galaxies were forming. Planet viewing is not great at the moment. Jupiter is lost in the solar glare; Venus and Mars lie low in the dawn glow. Saturn lies in the Southwest. The Moon will be Full on the 29th.

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

Naramata Slow is almost at its goal of raising $850,000 to save Centre Beach from being sold.
Final push is on to save Naramata beach by Oct. 31 deadline

Village has already raised 90 per cent of the $850K goal

RCMP. (Phil McLachlan - Black Press Media file)
Penticton RCMP cleared of wrongdoing after man seriously injured in custody

B.C.’s police watchdog found no evidence of harm caused by police in Sept. 21 incident

Apex Mountain Resort received 35 centimetres of fresh snow over the weekend, prompting some to head out for some early season turns. (Apex Mountain Resort / Facebook)
Stay off the mountain: Apex warns of early season dangers

Recreational use of the mountain before opening day comes with serious risks

The Penticton Indian Band is opposing any hunting of local big horn sheep which are an at-risk population. (submitted photo)
Penticton Indian Band oppose big horn sheep hunts

Local big horn sheep are an at-risk population

A house on Highway 3A caught fire Sunday evening, Oct. 25, 2020.
House fire on Highway 3A in Keremeos

Neighbours acted quickly to help save home

FILE – Provincial Health Officer Dr. Bonnie Henry provides the latest update on the COVID-19 pandemic in the province during a press conference in the press theatre at Legislature in Victoria, B.C., on Thursday, October 22, 2020. THE CANADIAN PRESS/Chad Hipolito
B.C. shatters COVID-19 records with 817 weekend cases; masks now expected indoors

Three people have died over the past three reporting periods

Kelowna Secondary School. (SD23 photo)
Second case of COVID-19 confirmed at Kelowna Secondary School

Interior Health has confirmed the new case is unrelated to the one announced Sunday

Summerland’s fallen soldiers and nurses are displayed on banners displayed around the community prior to Remembrance Day. (Contributed)
Remembrance banners depict Summerland’s fallen soldiers

Efforts to create banners began in 2000

The Stuart Park ice rink in January 2020. (Michael Rodriguez - Capital News)
Popular Kelowna outdoor ice rink will open amid COVID-19 pandemic

City council approved COVID-related changes to the Stuart Park ice rink’s operations

A nurse performs a test on a patient at a drive-in COVID-19 clinic in Montreal, on Wednesday, October 21, 2020. THE CANADIAN PRESS/Paul Chiasson
Interior Health sees 31 new cases of COVID-19 over record-breaking weekend

Eighty-six cases remain active and one person is hospitalized with the virus

Salmon Arm RCMP responded to a seven-vehicle chain reaction collision early Monday morning, Oct. 26. (File photo)
One person injured in seven-vehicle chain-reaction collision in Salmon Arm

Snow packed to ice, speed contributing factors behind collisions

RCMP responded to a single-vehicle collision on Highway 1 east of Salmon Arm early Monday, Oct. 26, 2020. (File photo)
Salmon Arm man killed in collision on Highway 1

RCMP say slippery road conditions contributing factor behind collision

Jordan Naterer, 25, was last seen Saturday Oct. 10. He planned a hike in the Manning Park area, and has not been seen since. Photo Facebook.
Parents not giving up, after official search for Manning Park hiker suspended again

‘We are determined, but eventually the money is going to run out.’

Most Read