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Skywatching

Searching for aliens

Our planet is surrounded by a sphere of radio waves. That sphere is expanding at the speed of light and now has a radius of about 100 light years.

A light year is the distance light travels in a year: just under 10 trillion kilometres.

In principle, if there is anybody on a planet orbiting a star closer to us than 100 light years, and has a sensitive radio receiver with a big antenna pointing in our direction, they would be receiving evidence of a technically-oriented species here on Earth.

In the 1960s, radio astronomer Frank Drake had the idea that if there are technically-oriented civilizations out there, at least some of them will be transmitting radio signals.

If so, a radio telescope here on Earth might be able to detect them. He was the one who formulated the famous Drake Equation, where one could put in estimates of numbers of stars with planets, and the proportion of those planets with life forms, and how many of them would be technically advanced, and how many would be using radio.

At that time most of those numbers were just blind guesswork, but the project seemed worth doing. So Drake decided to search for radio signals from alien civilizations.

We know there is life around at least one sun-like star, so he chose sun-like stars as being the best targets. Considering the huge cosmic distances, even the nearest star after the sun is 4.3 light years away, the signals are going to be very weak, so he chose pair of sun-like stars that are close to us: Tau Ceti (11.9 light years away) and Epsilon Eridani (10.5 light years).

The next big problem is what frequency to tune to. The radio spectrum is huge, with space for many billions of radio communication channels. For us here on Earth this is an advantage, because there is plenty of space for radio, TV, satellites, radar and all the other things we do with radio signals.

The problem is that not many of these will be easily detectable after travelling far out into space. These signals will be so weak that there is no question of putting on the headphones and tuning around until you hear something.

Each channel might have to be monitored for minutes or hours, just to collect enough signal. So all Drake could do is guess.

There is one frequency that most radio astronomers in the universe are likely to be monitoring. The cold hydrogen gas in the cosmic gas clouds radiates a radio signal with a frequency of 1420.405751 MHz — a wavelength of 21 centimetres.

If you wanted to send a signal to alien civilizations, you could probably count on someone observing at this frequency. So that is what Drake tried. He put a state-of-the-art receiver on a 26-metre dish and started to search. There were some false alarms, but nothing genuinely alien turned up.

Maybe that is not a good frequency to use. Here on Earth the hydrogen signal is so astronomically important nobody is allowed to transmit signals in the band. In addition, all that hydrogen emission in space could blanket weak alien signals. However, then what frequencies should we monitor? This leaves the choice more or less wide open.

Thanks to modern developments in digital signal processing, we can now monitor millions or even billions of radio frequencies at once. In addition, we have far more sensitive receivers. Of course, we still have to be pointing our antennas in the right direction at the right time.

However, we should be able to substantially increase the odds by using modern radio telescope designs that can monitor more or less the whole visible sky at once, covering millions of stars, compared with Drake’s “one star at a time.”

If those aliens are out there, working their radio transmitters, there is a pretty good chance that in the next decade, we will detect one of them.

Then, what?

  • Mars lies in the west after dark.
  • Jupiter, shining like a searchlight, rises around 2 a.m.
  • Saturn rises at 3 a.m.
  • The moon will be full on the 19th.




Space: the final frontier?

Somebody described space as what stops everything from being in the same place.

For a long time that is exactly how we saw it — a void, nothingness, with lumps and clouds of stuff sparsely scattered around in it.

Some of the lumps are big enough to generate energy, and shine, while others do not, and we see them because they are being illuminated by that light.

Space was simply the gap between things.

For a while, 19th-Century physicists thought space had to be more than that. They knew that waves need to have something to carry them.

For example, sound waves travel through air, and if the air was removed, there could be no sound. Most of us have seen the high-school science demonstration where a bell or radio is put under a glass bell jar and the air sucked out.

The sound gets fainter as the air is removed, until finally we cannot hear it at all. On the same logic, light waves need something to carry them through space. They gave this substance the rather magical name of the luminiferous aether.

However, two things then happened. Experiments that should definitely have detected this aether failed to do so, and then James Clerk Maxwell showed that light, and any other electromagnetic wave, such as radio, X-rays and so on did not need a medium to carry them.

So the aether evaporated and space was back to being an empty void. Then came Einstein et al.

In the universe as Isaac Newton saw it, everyone experiences space and time in exactly the same way. Our positions and movements in space would be seen exactly the same way by everyone else and all our watches would tell us the same time, no matter what we were doing.

For most of our every-day activities, this idea works fine. However, in the bigger picture, this picture fails.

In this new picture, space is rather like a multi-dimensional rubber sheet, which is distorted by bodies such as planets, stars and other bodies, like cannon balls sitting on a trampoline.

The force we call gravity is the distortion of the fabric of space by these masses. The expansion of the universe is more like an expansion of that fabric, with all the galaxies, stars, planets and other things just getting carried along by the current.

Time gets distorted too. This distortion now impacts our every-day life.

For GPS satellites to provide the navigation services we now take for granted, this deviation, although tiny, has to be allowed for.

For objects such as the Earth, the bending of space and time is small. However, for large or dense objects, such as neutron stars and black holes, the space and time can be severely distorted or even fractured, as at the event horizon of a black hole.

That is not the end of the story.

There are two ways you can have no money.

One is simply to have nothing.

The other is to have borrowed, say, $100 and therefore owe $100.

You have $100 and your lender now has 100 anti-dollars. If they are brought together, they bring us back to zero.

However, you can spend the $100 or invest it, earning interest. You create employment and drive the economy. In the same way, the lender can combine your anti-dollars with others, to make strange investment vehicles that also earn interest.

Now, we believe space is like that. On the smallest scales, particle pairs, particles and their anti-particle partners, are coming into existence and usually promptly cancelling each other out, like borrowing and paying back immediately.

However, if the particles get separated, for example one of the pair gets trapped in a black hole, the remaining one wanders off into the universe to take part in whatever is going on.

To paraphrase a famous physicist: these ideas are weird. However are they weird enough to be true?

We still have a lot to learn about that “empty, cold, void.”

  • Mars lies in the west after dark. 
  • Jupiter, shining like a searchlight, rises around 2 a.m.
  • Saturn is up at 4 a.m.
  • The moon will reach first quarter on the 11th.


Super-sized solar storms

On March 10, 1989, there was an explosion on the sun. It catapulted a large mass of hot solar plasma off into space at thousands of kilometres a second.

In the early hours of the 13th, this cloud, properly called a "coronal mass ejection,” hit us.

The Earth's magnetic field convulsed, triggering a major magnetic storm that caused power outages, disruptions of communications and somewhere around $2 billion worth of damage.

 In 1859, there was a far bigger solar storm. Back then the only hi-tech communications system was the telegraph. Operators got electric shocks off their equipment and, in some cases, it caught fire.

If we had another event like that today, the consequences would be enormous. We are now tied together by a complex communications, power and transportation infrastructure in a way that impacts almost all aspects of our lives.

Solar activity can black out radio communications and disable communication satellites. Solar-induced currents can cause failures in electrical power systems and enhanced corrosion in pipelines.

Enhanced high-altitude radiation due to solar activity can be a hazard to air travel on polar routes. Navigation systems can be disrupted, and on the ground, railway-signalling systems may be affected.

Imagine losing the Internet for a week, or, having put all your data in the cloud, finding you cannot connect to it. Until recently we had no information as to how big a solar storm could be other than the 1859 event.

Now, we know the sun can do far "better" than that.

Although our medieval ancestors would not have noticed solar activity and solar storms much, apart from occasional displays of aurorae, those storms left some environmental signatures.

Solar activity changes the intensity of high-energy particles hitting the upper atmosphere. When these particles hit atoms of oxygen or nitrogen, they create new elements, some of them radioactive.

These new elements get carried down in rain and snow to the Earth's surface. In most places they just diffuse off into the soil. However when these atoms fall on permanent ice caps, they end up being trapped in a layer of surface ice.

Then, the following year another layer forms on top, and so on, so that the icecap contains a historical record of solar activity. Scientists have extracted ice cores yielding solar activity records dating back to remote historical times.

When we look at these ice cores, we can see the annual layering quite easily, so we can scan along the core looking for particular elements, counting the layers as we go. Doing this we can track solar activity back in time thousands of years.

It has been found that although our hi-tech free ancestors never noticed, there have been solar storms far larger than anything of which we had prior knowledge.

One hit the Earth in 660 BCE (BC). Others occurred in 775 and 994 CE (AD).

Our vulnerability to bad solar behaviour is now at an all-time high, so the big question is when will the next supersized solar storm happen? Can it be predicted? How much warning will we get?

In Canada, we are monitoring the sun every day and have an extensive set of instruments monitoring the Earth's ionosphere and magnetic field.

We are trying to get a better understanding of the connection between what the sun gets up to and what the consequences would be here on Earth.

Working with international partners, our aim is to minimize what the sun can do to our modern, technology-dependent way of life.

This involves prediction of dangerous solar activity, assessment of its potential impacts, and developing means to mitigate them, and where there is damage, making the recovery as rapid as possible.

We will solve these problems because we have to.

  • Mars lies in the southwest after dark. 
  • Jupiter rises around 2 a.m.
  • Saturn rises around 3 a.m.
  • Venus lies low in the dawn glow.
  • The moon will new on the 5th.




Working on the moon

One day, we will have observatories on the moon.

Since the moon has no atmosphere, they will encounter no cloudy nights and all the cosmically interesting radiations from space will reach the telescopes.

There will be no street light glare or other human-made light pollution, our radio interference will be over 400,000 km further away, and if we put our telescopes on the other side of the moon, never above our horizon. There is another huge advantage to putting telescopes on the moon. We can have people nearby to operate, maintain and upgrade them.

Orbiting telescopes such as the Hubble Space Telescope avoid the problems of trying to observe from the Earth's surface, but at the expense of an instrument that has to survive the rigours of being launched, deploy its equipment automatically and then work reliably for years. That is very hard.

Imagine a cluster of optical, X-ray, infrared and radio telescopes surrounding a lunar base housing scientists, engineers, technologists and others.

The base will contain the laboratories, workshops and living space needed for long-term occupation. It will be something like one of our bases in the Antarctic, designed to support living and working in an extremely hostile environment.

The absence of an atmosphere, which is an astronomical advantage, is also a challenge. Many of the radiations from the sun and elsewhere in the cosmos are hazardous to living creatures. An atmosphere provides an insulator and heat trap, making Earth temperate and mostly comfortable.

Without this, the moon's surface experiences daily temperature variations ranging from above the boiling point of water to below a hundred degrees Celsius below zero.

On the plus side, guaranteed sunny weather every day makes solar power a good option for providing electricity to the telescopes and to the Moon Base.

The temperature changes and radiation levels on the surface make it an undesirable place for long-term human habitation.

However, a few metres underground the temperature is an unchanging minus 50 Celsius, which is much easier to live with. It gets colder than that in Canada;  minus 63 degrees C has been recorded in the Yukon.

Ice has been discovered on the moon. This is good news because it means water won't have to be expensively imported from Earth, and with abundant electrical power, oxygen for breathing can be obtained from that water.

Greenhouses lit and heated by locally generated power, and irrigated with locally obtained water would provide at least some of the food requirements of the local inhabitants. However, that ice could also provide an engineering challenge, as it does in the Arctic.

There is a lot of ice in the ground in the Canadian Arctic. It is called permafrost because under normal conditions it never melts. If for some reason it does melt the ground collapses and so do any buildings sitting on it. To avoid heat from those buildings melting the permafrost, they are mounted on piles so that there is an air gap between their floors and the ground.

The situation with the Moon Base will be a bit more complicated, since it will actually be in the ground. The engineering challenge will be to ensure the ground in contact with and supporting the base will always remain well below zero. However, there are buried buildings in the Antarctic and other places, so we are at least part way to a solution.

At the moment the biggest impediment to setting up and running a base on the Moon, with a good collection of scientific instruments, is not the engineering of the base itself, but more the transportation problem. How do we get there?

  • Mars lies in the southwest after dark. 
  • Jupiter rises around 2 a.m.,
  • Saturn rises at 4 a.m.
  • Venus rises at 5 a.m., in the predawn glow.
  • The moon will reach Last Quarter on the 27th and be New on May 5.


More Skywatching articles

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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]



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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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