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Skywatching

Light pollution is stopping us from seeing the night sky properly

The cost of hiding the stars

We're a funny species. On one side, we like to lie on our backs by lakes in the woods, or at other dark places, and enjoy looking at a starry sky. Poets, artists and composers romanticize it. Astronomers look though this window at the rest of the universe.

But this contrasts with the results of a study just published that says light pollution continues to get worse, and in more and more of the world the stars are getting harder to see. Another side of this paradox is our work on obliterating our view of the stars is consuming an increasing amount of energy and lots of money.

It is easy to see this process happening. For example, we all agree decent street lighting improves safety and security. The objective of this lighting is to put light on the road and what is happening on it. The light that is not directed downward onto the road is wasted light, electricity and money.

If we stand on a hill overlooking a town, and can see the actual streetlights—as opposed to what their light is falling on—we are seeing wasted light. Light should be sent down towards the road not upward in our direction.

Looking down from a plane shows it better. From the International Space Station, the world shines like a beautiful jewel box because of the light being wasted by squirting it upwards.

Imagine we need to put a bit of light over our backyards, and install an unshaded light. Without a shade, half the light goes down onto the yard, and the other half goes upward, helping make the Earth look pretty for astronauts on the International Space Station. If we put a proper shade over the bulb, we can reflect the upward-going light downward, so that it does something useful.

Maybe a single, 100-watt bulb doesn't sound like much, but over a year the energy wastage and unnecessary cost add up. Now imagine millions, or billions, of people doing that. In addition, having a brilliant yard light spilling off your property into the eyes of the neighbours is a way to waste money while getting people upset at you.

Shopping centres and public places where customers and visitors park their cars need to be lit. In fact, lighting them probably costs a fair amount of money. A bit of planning beforehand, selecting appropriate shading and positioning of the lights can provide what is needed with a significant saving in energy.

Our local community administration has installed some very nice LED (light emitting diode) street lamps. They light the road and the bottom part of the cliff near the road very effectively. They spill so little light upwards that from above they are visible only as silhouettes against the pools of light below.

As we move into a world where we want to cut back and eventually cease our use of fossil fuels, and move on to other sources of energy, reducing wastage of energy will make the transition easier. It will also cut back the amount of carbon dioxide we are releasing into the atmosphere, while hardly affecting our way of life at all.

In professional astronomy, we can survey the world to find the places where the skies are darkest, clearest and steadiest. We can also put telescopes in space. However, there are far more amateur astronomers than professionals, and their ability to enjoy the sky is controlled by the environment they find themselves in.

“Dark sky” reserves are being set up across the country, where we can enjoy the dark, starlit sky, either with a telescope or binoculars, or just lying on a blanket, looking up. However, for those who have to enjoy the night sky from their backyard, just imagine how much they will thank you if you set up your yard light so its light stays on your property.

•••

• Venus shines brightly, low in sky in the sunset glow, with Saturn, much fainter, nearby.

• Jupiter lies in the south-west, with Mars high in the south.

• The Moon will be full Feb. 5.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.





The age-old question: Is there life on other planets?

Are we alone?

One of the planets being studied with the James Webb Space Telescope is about the size of the Earth.

However, it lies so close to its star that it only takes four days to complete each orbit. Our planet takes a year to move round the Sun. Mercury, the closest planet to the Sun, takes 88 days.

That distant world is almost certainly a ball of lava. The reason for the interest in such a world is to learn more about how planets evolve. If there is any sort of life there, it will be so utterly bizarre it would be hard to work out how to look for it.

Thousands of worlds have been found so far, so surely, if life colonized our world, there must be other worlds out there with living things on them.

Since we use radio waves for many things, then maybe technically advanced civilizations on other worlds may do the same thing. Even if they are not transmitting “we are here" signals, their radio transmissions for local use will be radiating off into space.

Our uses of radio are so universal that the leakage of those signals out into space makes our world the brightest planetary radio source in the Solar System. Any visiting alien spacecraft should be able to pick up our signals and determine which world to visit - or to avoid.

However, life has been present on our world for over 3.5 billion years, but we have only been using radio for a century or so. Moreover, intelligent marine life on a water world would have little use for radio. We need to come up with other search methods.

Even through the biggest telescopes, most stars just appear as tiny dots. The main way we search for planets is to monitor the brightnesses of as many stars as possible, looking for tiny dimmings as their planets move between the stars and us. A downside of this search method is that it works really well at detecting big planets orbiting close to their stars, but less well for small planets like ours, orbiting further out, where they won't fry.

So our list of planets we have found orbiting other stars almost certainly does not give us a complete picture of the population of planets out there.

Despite this difficulty, we are finding planets where liquid water can exist on their surfaces. That seems to be a key need for life as we know it. But what about life as we don't know it? On Titan, the largest moon of the planet Saturn, temperatures are so low that water is a solid, rock mineral. Instead there are rivers and lakes of liquid methane and other hydrocarbons, sustained by liquid methane rain. Could there be some form of life there? We need some more general ideas as to what is evidence of life.

On our world we have weather, with water circulating from clouds to land, to the sea and back again, moving nutrients around. Also, on the whole, conditions are stable enough to allow living things to survive and proliferate. This would apply to living things everywhere, even creatures living in thousand-degree plasmas in magnetic fields. So moderately dynamic worlds are a good bet.

Another possibility is to search planets for things produced by life processes. On our world, oxygen is present because of plant life, and the only reason there has been oxygen to breathe for all the time life has been present on our world, is that the plants are continually topping up the supply.

Even though we are seeing other worlds only when they pass in front of their stars, by studying the changes in the starlight as they do, we can detect their atmospheres and search for chemical signatures of living things.

We can also get an idea of how stable or dynamic those worlds are. So we have what we need to make a good start in finding out if our living world is alone in the universe.

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• Just after sunset, Venus shines brightly, low in the south-west, with Saturn, much fainter, nearby.

• Jupiter lies in the southern sky, with Mars high in the south-east. The Moon will reach its first quarter on Jan. 28.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



Hisses, whistles and clicks—the sound of the magnetosphere

Listening to the solar wind

Quite a few years ago now, an ionospheric physicist and I were a long way up a dirt, logging road in Algonquin Park, in Ontario.

The idea was to get a long way from civilization and especially power lines. Finally we found a place where we could safely pull off the road, just in the unlikely case a vehicle happened to come along.

We were out there in the woods to conduct an interesting experiment, to listen to and record the solar wind rubbing on the Earth's magnetic field.

We first deployed the antenna. This was about 35 metres of 10-core electric cable (a cable consisting of 10 individually insulated wires). This we laid down on the ground by the road in the form of a more-or-less circular loop. The wires were connected so the cable formed a large, 10-turn coil. This was to be the antenna.

The receiver used in this experiment was not a radio receiver, it was a simple audio amplifier, similar to what we would use with a microphone and speaker at a concert or public event.

However, this one was battery powered and only produced a strong enough output to listen to by using a pair of headphones, or to connect to a battery-powered tape recorder (remember, this was years ago).

While recording, we could listen to the signals using the speaker in the tape recorder.

By the time we were up and running it was dark. The sky was clear, with countless stars. It is interesting that when we are under a really dark, clear sky, the sky looks grey.

The tall trees on either side of the road were black against the sky. It was a fascinating and magical experience, and would have been more so if we were not most of the time confined to the car because of the mosquitoes.

Unlike most signals studied in radio astronomy, the sounds we were recording were definitely worth listening to. There were long, warbling whistles, rising and falling in pitch. Occasionally there were strange hissing sounds, and lots of clicks.

Under all this was a faint hum, coming from a power line around 60 kilometres away. That's why, to do this experiment, we had to get as far as feasible from people, our appliances and power lines.

If it were left undisturbed, the Earth's magnetic field would be a sort of thick doughnut shape, with lines of magnetic force passing high over the equator and then diving down to the northern and southern magnetic poles. However, the solar wind, a blast of particles and magnetic fields hits the Earth's magnetic field and blows it out into a long teardrop shape, with the pointed end facing away from the Sun.

The place where the solar wind and our magnetosphere meet is known as the “magnetopause.” Inside it, we are in the Earth's magnetic domain, and on the outside the Sun is in control.

The Earth's magnetic field plays an important role in protecting astronauts in low earth orbit from the effects of the Sun's bad behaviour.

Where the solar wind rubs the magnetopause, it acts on the lines of magnetic force in a similar way to what the bow does to a violin string, or a finger rubbing on glass. It excites waves. These waves move along the magnetic field lines, following them downward into the magnetic polar regions, which include Canada.

Some of those lines of magnetic force passed through our coil of wire, exciting electric currents, which we amplified and recorded. Those waves were at low frequencies, which were audible to the human ear, so all we had to do was capture, amplify and record them.

It is intriguing that some of the most weird and obscure physical processes in astronomy are happening just a few thousand kilometres above the Earth. The same sorts of waves have been detected in Jupiter's magnetosphere by space probes.

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• After sunset, Saturn lies low in the southwest, a bit higher than Venus.

• Jupiter is high in the south and Mars even higher in the southeast.

• The Moon will be new on Jan. 21.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.





The era of really huge telescopes has arrived

Giant telescopes

An optical telescope with a mirror 30 metres in diameter is being built. Also under construction is the largest radio telescope in history.

This need for increasing size comes from our desire to study the very earliest observable history of the universe. It means observing objects more than 13 billion light years away. Objects lying at such distances are extremely faint and any radio emissions reaching us from them very weak.

Until recently the optical telescope with the largest mirror was the Hale Telescope on Mount Palomar, which has a mirror 200 inches (more than five metres) in diameter. That was about the biggest mirror achievable at the time with available technologies and materials. As the telescope changes position, the mirror sags and flops. This was minimized by making the mirror very thick. However, that made it heavier, making the flopping and sagging forces larger. Eventually a point is reached where adding more material makes the situation worse. About five metres seems to be the largest we can make mirrors in single pieces that will stay in shape.

The great leap forward that makes it possible to build telescopes with bigger mirrors came about due to advances in computer control technology. Today we can make mirrors thinner, which makes them lighter and easier to mount. It means they will be very floppy. However, in the new telescopes, behind the mirror is a large number of computer-controlled actuators. If the mirror flops or sags, the actuators push or pull it back into shape again.

As the telescope looks around the sky, the changing sags and flops are continually corrected. Thanks to this technology, if a mirror is too big to make in one piece, we can make it in sections, all individually controlled with clusters of actuators. These developments have made it possible to start construction of a really large optical telescope, one with a mirror thirty metres in diameter.

Most of the older radio telescopes are large, single dishes. The bigger the dish, the greater the sensitivity and the more detail it can map. Those instruments just told us the strength of the radio emissions from a particular point in the sky; we made images by scanning the antenna around the region of interest. It is hard to build a single dish bigger than about 300 metres.

However, we can make larger radio telescopes out of lots of smaller ones. The ability to sense detail depends on the size of the cluster of antennas, and the sensitivity is set by the total signal collecting area of all the antennas. These array radio telescopes can be used to make images using a process called "aperture synthesis", a process pioneered in the United Kingdom and Australia. The main instrument at our observatory is a seven-antenna radio telescope, which uses this technique.

An array of 512 tightly clustered six-metre radio dishes are under development at our observatory, it will resemble the eye of a giant fly. An international project is under way build a radio telescope comprising thousands of small dishes, with a total signal collecting area of about a square kilometre.

In principle the maximum size we can now achieve with a radio telescope is the amount of the Earth's surface where we can see the same cosmic objects at the same time. Actually, recent experiments showed we can add space-borne antennas to ground-based arrays of telescopes, giving us radio telescopes bigger than the Earth.

Much of this great leap forward has been made possible by advances in digital control systems and computer power.

We will depend on these technologies to deal with the tsusami of data these new instruments will raise. How can we archive, process, access and search it?

•••

• After sunset, Saturn lies low in the southwest, Jupiter higher in the south and even higher in the southeast. Venus lies very low in the sunset glow.

• The Moon will reach first quarter on Jan 14.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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202006
About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected].ca



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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