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Skywatching

Into the unknown

On New Year's Day, the New Horizons spacecraft had a close look at the most distant object yet explored, a snowman-shaped lump of ice and rock known as Ultima Thule, which translates as "the edge of the known world"” or "the beginning of the unknown.”

This space mission is showing us amazing, new things and is a monument to engineering achievement and space navigation. Why make this huge effort? Why is it important?

Basically, it is part of our quest to understand where we came from — how did we get to be here?

Our solar system formed some 4.5 billion years ago, from the collapse of a huge cloud of cosmic gas and dust. The Earth and other planets were at first huge balls of molten rock. These eventually cooled, so that by about 3.8 billion years ago, our Earth, and probably Mars, had cooled enough for oceans, lakes and rivers of liquid water to accumulate on its surface.

In that water were the organic chemicals that form the basis of life as we know it, and around 3.5 billion years ago, living things had appeared in our oceans, and maybe at other places in the solar system.

Those chemicals cannot survive in molten rock. How did they manage to be here when needed? Where did we get all that water? The history outline given here does not answer those questions.

Looking at our Earth or other planets such as Mars does not help us. Even the oldest rocks on Earth are not the original stuff. Everything here has been affected by plate tectonics, a process which continually recycles the Earth's material.

Mars cannot help us here. Even the material of the airless, lifeless moon is not original. Fortunately there is still a lot of unused solar system construction material left over. However, it lies several billion kilometres away, in the dark, cold outer reaches of the solar system. This is our "deep freeze": too cold for anything to evaporate or to change over time. The material is orbiting the sun in a great cloud known as the Kuiper Belt.

We want a close look at some of that material, to see what is like and what it is made of. However, in at least one case, things are not as cold, dark and quiet as we believed.

The New Horizon's space mission started on Jan. 19, 2006, with the launch of the spacecraft from Cape Canaveral. Pluto used to be known as the ninth and outermost planet of the solar system.

However, recently it became clear it was another sort of thing altogether, one of the largest and closest of the bodies making up the Kuiper Belt. The New Horizons space mission was to send a space probe out to Pluto, to give us our first close look at it and its moons, and then to continue outward, for a look at other Kuiper Belt Objects.

The mission has proved a stunning success. It passed Pluto during the summer of 2015 and ended our idea of Pluto and its moons being cratered, icy rock balls having seen no change for billions of years.

Instead, Pluto is a geologically active world, with an atmosphere and weather, frozen nitrogen glaciers, collections of organic chemicals, dunes, and features similar to the permafrost structures we see in the Arctic.

Still working well, the spacecraft continued outward, and the next object to visit was selected: a Kuiper Belt Object known as Ultima Thule.

This one looks more like what was expected, but that impression probably won't last long as the data continues to flow in over the coming months.

Moreover, the spacecraft continues to work well, and there is some fuel left, so it will be possible to look at another object or two. Since our explorations now extend beyond Ultima Thule, maybe we will need to rename it.

  • Mars, fading as it recedes, lies in the south after dark.
  • Venus shines like a searchlight in the eastern sky in the early hours
  • Jupiter shines low in the dawn glow.
  • The moon will be full on the 21st.


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Water, water everywhere

Thirty-some years ago, one of my radio astronomy colleagues at NRC pronounced that "One way or another he was going to detect water on Mars.”

This was years before there would be any prospect of landing a spacecraft on the Red Planet and look around for water.

He was using a large radio telescope - the 46-metre dish at the Algonquin Radio Observatory, in Ontario. That instrument, equipped with what were at the time state-of-the-art receiving systems, had played a part in a number of world radio astronomy "firsts,” and was well suited to the job.

The idea was to look for a characteristic radio emission produced by water molecules. This radio signature is at a wavelength of about 1.35 cm.

The idea was simple, to point the dish at Mars for long periods, hoping to collect enough signal to add up to a detectable "spike" at that wavelength. Unfortunately, despite intense efforts, he was not successful.

Although we now know there is a lot of water on Mars, there is not much of it in the atmosphere, where it would be producing that radio signature.

Despite problems like this, studying the radio signatures of water and other molecules has become an extremely important branch of astrophysics.

It shows us what is going on in those dark, cold cosmic clouds and gives us important insights into the processes that made the foundation for the appearance of living things.

The most important radio signature of the lot is that of cold, neutral hydrogen gas in space. Since hydrogen is the most common element in the universe, and is involved in the formation of stars, galaxies and other things, it is a powerful stethoscope on cosmic processes.

The radio signature has a wavelength of 21.1 cm. Since there is a lot of hydrogen out there, the signal is a strong one and relatively easy to pick up.

From the number of icy objects we can see in space, we can conclude there is a lot of water out there, and despite that lack of success with Mars, we are detecting its presence in most cosmic clouds.

There are lots more radio signatures that have been detected, such as ammonia, at about 1.3 cm wavelength, formaldehyde (6.2 cm wavelength), carbon monoxide (2.6 mm), methanol (4.5 cm) and many others.

Most of these molecules radiate their radio signatures at very short (millimetre) wavelengths. Since their relative concentrations and reactions tell us much about star and planet formation, and about life, cosmic molecules have become a very important branch of astrophysics, and special radio telescopes have been built to observe them.

Two such instruments in which Canada has participated are the James Clerk Maxwell Telescope, on Mauna Kea in Hawaii, and the Atacama Large Millimetre Array, in Chile.

The problem now is that although a very large number of molecular signatures have been detected we have as yet only identified a fraction of them.

In the cold, dark, cosmic dust and gas clouds, the elements produced by stars will react very slowly, but billions of years have been enough time for a lot to have happened.

Laboratory experiments have shown us that under the right conditions, in the atmospheres of young planets, they can react to form amino acids, the building blocks of proteins and life as we know it.

This may give us the impression cosmic processes favour the formation of carbon-based life, like us. However, that conclusion is a bit premature.

We are, of course, biased toward searching for life processes with which we are familiar, like ours. What are those unidentified molecules up to?

Can there be life that is not based on molecules at all? In our huge, old universe, almost anything is possible. We need to keep our telescopes going and our minds as open as possible.

  • Mars, fading as it recedes, lies in the south after dark.
  • Venus and Jupiter shine low in the dawn glow.
  • The moon reaches first quarter on the 13th.


Long trip away from home

In 2013, Voyager 1 left the solar system, moving at around 62,000 km/h.

In the last few weeks, Voyager 2 followed.

They bear messages to any alien civilizations that might find them, including recordings of sounds of Earth. However, space is so huge, it is unlikely anyone will come across them.

Launched in 1977, the two spacecraft were intended to give us close views of the outer planets. Back then we did not have the technology to slow the spacecraft down to go into orbit around those planets.

They just shot past at high speed, taking pictures and making other observations as they went. As seems usual these days, the results that came back from those robot explorers have forced us to discard a lot of our favourite theories about the working of the outer solar system.

When we fly outward from Earth, we eventually reach the magnetopause, where our planet's magnetic field ends and we enter the realm of the solar wind.

There is a definite point at where we leave Near-Earth space and enter interplanetary space. The solar wind flows outward past all the planets, with most of them having their own backyards, enclosed by their magnetic barriers.

Eventually, the solar wind meets the magnetic field of our galaxy, the Milky Way. The meeting point is called the heliopause.

Inside the heliopause, we are in the solar system, beyond we are in interstellar space. The solar system is our cosmic backyard, and we are now venturing over the back fence into interstellar space.

This brings us face-to-face with unimaginably huge distances and spans of time. Light takes about 100,000 years to travel from one side of our galaxy to the other, so we say it has a diameter of 100,000 light years.

Light takes about eight minutes to travel from the sun to us. The solar system is less than a light day in diameter, and it took the Voyager spacecraft since 1977 to reach the heliopause. The nearest star after the sun lies 4.3 light years away.

If Voyager 1 were heading in the right direction, it would take around 80,000 years to reach it. Images from the Hubble Space Telescope show millions of galaxies, extending out billions of light years from us.

To explore even our own galaxy would require spacecraft able to travel at huge speeds, far faster than anything we can achieve now. This brings us to Mother Nature's speed limit.

Albert Einstein showed, and experiments have proved him right, that any material object cannot travel faster than the speed of light. At that speed, it would still take 4.3 years to get to the nearest star. However, as we get closer and closer to the speed of light, funny things happen to time.

We could return from our trip to the nearest star, after a two-way journey time of nine to 10 years, depending on how long we spent exploring, and find that centuries or millennia had passed on Earth.

For all intents, we would have to regard the trip as one-way, because when we got back, everything we were familiar with would be long gone. In science fiction, this problem has been "solved" with ideas like "warp drive", "jumps through hyperspace" and so on.

The latest work in physics suggests such things might well be possible. However, at the moment, we have no ideas as to how we can make them happen.

One stunning thing we have found from our space probes out there exploring the solar system is how long they have continued to work. Probes have been sending us back data after decades or more.

One explanation for this might be that those robots are well beyond the reach of engineers and scientists who have bright ideas as to how to tweak those devices to make them "work better.”

Since this is my last article for 2018, I am taking this opportunity to wish you a wonderful Christmas and a Happy New Year.

  • Mars lies in the south after dark
  • Venus shines low in the dawn glow
  • Mercury and Jupiter below it.
  • The moon will reach last quarter on the 29th.


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Winter solstice is coming

At 22:23 Universal Time Dec. 21, that is 14:23 PST, the sun will reach the southernmost point in its yearly travels across our skies; the winter solstice.

We will have the day with the minimum length of daylight. After that the days start to lengthen.

Even in our modern hi-tech world, with artificial light and heat, we look forward to spring; imagine how our ancestors felt about it.

They were certainly very good at recording the patterns of things they saw in the sky: the movements of the sun and the moon, and the weird moving to and fro of the planets against the stars.

They identified the daily and seasonal movements of the sun, including the solstices and equinoxes, predicted eclipses, made a workable calendar and many other things. However, what they were seeing was made really hard to interpret because they were sitting on a spinning ball, hurtling around the sun, while looking at the other planets as they do the same thing.

To understand the seasons, equinoxes and solstices, forget you are on the surface of a spinning, orbiting ball; imagine you are looking at the Earth and Sun from far out in space.

Our Earth and the other planets move in more or less circular concentric orbits around the sun, all in the same plane.

In addition, the Earth is spinning, like a top, with its axis tilted from upright by about 23 degrees. The direction of that lean varies extremely slowly, over tens of thousands of years, so it is unchanging as far as most of us are concerned.

Completely fortuitously, for most of our history the Earth's spin axis has been pointed at a star, which we call Polaris, the North or Pole Star. Therefore, as the Earth moves around the sun in its annual travels, there is a point where the Northern Hemisphere is leaning toward the sun, and another point, six months later, on the other side of the sun, when it is leaning away.

When the lean is toward the sun, we get the largest number of hours of daylight each day, and the sun is highest in the sky at noon. It also rises and sets at its northernmost points on the horizon. This happens around June 21 and is called the summer solstice.

When the lean is away, we get the smallest number of hours of daylight and the sun at noon is at its lowest in the sky. Sunrise and sunset are at their southernmost extremes on the horizon.

This happens around Dec. 21 and is called the winter solstice. There are two intermediate points, where the Earth is leaning sideways with respect to the direction of the sun, neither leaning toward or away.

These are called the equinoxes, because at that time we get equal hours of daylight and darkness. We get one around March 21 when the sun is heading north, the spring equinox, and one around Sept. 21, when it is heading south, the autumn equinox. On Dec. 21, the sun will start moving north, imperceptibly at first, but then faster and faster.

Here are two last-minute Christmas present suggestions. Your local science store will probably have them. All backyard astronomers need a planisphere. The ones worth getting consist of two plastic discs. Don't buy a cardboard one.  Remember it is likely to be dropped in mud or snow.

On the lower disc there is a starmap with a calendar around the edge. On the upper there is a window showing part of the starmap beneath, and time of day round the edge. Match the local standard time on the upper disc with the date on the lower disc, and the window will show the constellations that are above the horizon.

Make sure you get one for your latitude.

The second is the Observer's Handbook, published annually by the Royal Astronomical Society of Canada. It is a gold mine, filled with astronomical information and listings of the coming year's astronomical events.

  • Mars lies in the south after sunset
  • Venus shines low in the dawn glow
  • Mercury and Jupiter are below Venus
  • The moon will be full on the 22nd.


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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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