Kicking up a lot of cosmic dust

Dust in space

By now most of us must have seen the incredible images produced by the James Webb Space Telescope.

Then of course, there are the beautiful images obtained using the Hubble Space Telescope. The images obtained using ground-based telescopes, such as the Canada France Hawaii Telescope are pretty stunning too. The interesting thing is that the stuff that makes those images so spectacular is dust and gas. Without it the images would "just" show lots of stars.

The clouds are being hit by equivalents of the solar wind given off by stars. In other places they are being blasted by the explosions of dying giant stars. All this, together with the flows and eddying of the clouds as they move through space, produces all sorts of structures, including rings, shells, blobs and towers.

These are lit up by stars. In addition, ultraviolet light from those stars makes the gases in the clouds fluoresce, glowing red, pink and other colours. The result is those amazing images our telescopes are giving us.

However, in many ways, some of the most exciting stuff is happening in the dark, cold clouds, which we only see with our radio telescopes, or where they lie against a bright background of glowing gas. It is in those clouds that we believe the ingredients for life are produced. In many ways those clouds are like the soil in our fields and gardens. Billions of years ago, the soil was just pulverised rock, like the soil (also called regolith) on the Moon.

Then the first, primitive plants appeared, obtained nourishment by breaking down the rock minerals, and when they died, added their organic remains. So today, our soil is made up of rock minerals and material from generations of plants. It is the reservoir to which materials return and where new life obtains its nourishment.

The cosmic dust and gas clouds are the universe's soil. In the beginning it was just hydrogen and helium. Waste materials from dying stars added all the known elements. Over eons, in the cores of cold, dark clouds, these elements combine to form a witches' brew of chemicals.

These chemicals have signatures we can detect with our radio telescopes, so we know something about the chemical reactions going on. The problem is not in detecting chemicals. The problem is that there are so many chemicals, and so many signatures, it can be a challenge to identify them.

When we put a mixture of the most common cosmic chemicals together in the lab, and hit the mixture with ultraviolet light or electrical discharges, we get a dark gunk that contains amino acids. These are the building blocks of proteins, which are fundamental to life as we know it.

Radio telescopes have detected simple amino acids in those dark, cosmic clouds. The idea that the seeds of life arrive on a new world from out there in space has been around for decades. It is called "panspermia". When planets form from cosmic gas and dust, they get a ration of amino acids and other organic chemicals that could form the foundation for the appearance of life.

However, although it is true that aminoacids are the building blocks of proteins, one protein molecule can contain up to thousands of amino acid molecules. What can make cosmic amino acid molecules combine in large numbers in a precise way is not yet understood.

A pile of bricks very rarely turns into a building all by itself. Maybe the precise conditions on the young planet determine whether this assembly happens and gets what we would call life started. This step probably dictates how widespread life is in the universe. We can be sure that, even sharing their chemical origins, those aliens won't look like us.

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Mercury, the closest planet to the Sun lies low in the sunset glow. Venus, the next planet out, shines brightly above it, and Mars, planet 4, is still high in the south. The Moon will be Full on the 5th

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

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

Inhospitable planet only beautiful from far, far away

Volcanoes on Venus

Venus is one of the most beautiful sights in the sky.

That brilliant, white spark in the morning or evening star got it referred to as Phosphorus "The Morning Star" and Hesperus "The Evening Star". The beauty of the planet got it to be named after Venus, the Goddess of Love.

However, we now know that Venus is one of the most hostile places in the Solar System. Under a deep layer of cloud is a torrid surface hot enough to melt lead and tin and the atmospheric pressure is around 90 times the atmospheric pressure on the surface of the Earth.

The survival record for a lander sent to the surface is around 20 minutes. Radar images of the surface show undulating terrain with many volcanoes and lava flows. Some of the volcanoes are old and probably extinct, but there are others that appear to be active.

Some of the volcanoes are flat domes, others resemble pancakes and some are long fissures that are erupting lava. To understand volcanoes on Venus and on our world we need to go back the two planets' early history.

Around 4.5 billion years ago, Earth and Venus were balls of hot, molten rock. Over time the heavy materials such as iron and nickel and rocks containing them sank towards the middle and the lightest stuff, a scum of silica (sand) and aluminium minerals accumulated on top.

The Earth also had a surface layer of water. It looks as though Venus never got cool enough for water to accumulate. The water plays an important role in plate tectonics. As far as we have found so far, Venus shows little sign of plate motions. There is, however, a heaving and cracking of the surface as magma moves around inside the planet.

On our world we have two main kinds of volcano. One has steep cones and erupts explosively. Mount St. Helens and Vesuvius (the volcano that buried Pompeii) are examples. Mount Krakatoa was another. In 1883, it exploded in one of the biggest explosions in recorded history. The volcano completely destroyed itself. A "Son of Krakatoa" is now slowly building.

The other kind of volcano forms a much flatter hill, erupting much more gently, producing huge lava flows in eruptions that can continue for decades. These are known as shield volcanoes. The Hawaiian Islands were formed in this way. A new island is forming but has not yet emerged above the sea.

The explosive volcanoes form above subduction zones, where one tectonic plate is pushed down under another. Seawater and silica from the surface gets carried down, where it melts and combines with the molten rock producing a viscous, sticky lava pervaded with highly-compressed superheated steam. The sticky lava plugs the volcanic vent. The steam pressure builds until the volcano explodes, showering lava powder (ash), superheated gases and lava over the surrounding land.

Then, gradually the volcanic cone starts to rebuild. The lava forming the shield volcanoes comes from deep down, and contains little silica and no water. It runs freely and can cover large distances before solidifying.

Many of the volcanoes on Venus are huge shield volcanoes. This would be expected, with no plate tectonics and no water getting added to the molten rock. Some of the volcanoes show evidence of viscous lava. Probably, over time, the silica-rich material on the surface got buried deeper and deeper under lava flows, until it joined some of the underground magma, making it viscous.

However, without the superheated steam, the eruptions would usually not be explosive. With the high surface pressure and temperature the lava would remain runny for longer.

Venus is a fascinating world, like ours in some ways, but in other ways bizarre and hostile. Manned visits are unlikely.

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• Jupiter has disappeared in the sunset glow, leaving Venus shining brightly.

•Mars lies high in the south. Saturn is very low in the sunrise glow.

•The Moon will reach its first quarter on March 28.

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

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

Making really big telescopes

Getting better view of space

Conjunctions and 'rising worms' in space

Movement of planets

On March 2, the planets Venus and Jupiter were within half of a degree of each other in the western sky after sunset.

That is closer together than the width of the full Moon. They are still fairly close together but getting a bit further apart every night. These close encounters, known as conjunctions, are a beautiful consequence of the way the planets move around the Sun in their orbits.

Conjunctions between the planets, along with eclipses of the Sun and Moon, and the movements of the Sun, Moon and planets among the stars, were familiar to our ancestors. Even though they did not understand what was going on, they could predict astronomical events precisely.

Back in those remote days, the science of astronomy had not yet separated from the pseudo-science of astrology, and events like conjunctions, eclipses and the positions of the planets among the stars were widely regarded as portents. This is probably why two royal astronomers were executed by their angry King for not telling him an eclipse was due. The predictive skills of those ancient astronomers came from the combination of painstaking observations and the identification of patterns and rhythms in the movements of objects in the sky.

All the known planets orbit the Sun in concentric, almost-circular orbits. Starting from the Sun, we have Mercury that races around the Sun in about 88 days, Venus, with a lap time of 225 days. Our planet takes a year (365 days) to complete one trip around the Sun. Continuing outward there is Mars (687 days), Jupiter (12 years), Saturn (29 years), Uranus (84 years), and Neptune (165 years).

Since all the planets are orbiting in almost the same plane, it is inevitable that from our position on Planet 3, on occasion we would see pairs of other planets lying in the same direction, appearing close to one another even though in reality they are far apart.

If all the planets orbited in exactly the same plane, close encounters between planets would be very common, with planets passing precisely in front of another. However, because the planets do not orbit precisely in the same plane, these encounters are very rare, and close encounters like the one we have just seen (unless it was cloudy) are pretty rare too.

Our ability to comprehend the motions of the planets has been made complicated by our being forced to make our observations from one of those planets, spinning on its axis as it orbits round the Sun. This means planets appear to move in one direction among the stars, and then reverse course for a while before returning to their original directions.

Because these motions repeated, our ancestors decoded their rhythms and used that knowledge to predict future movements, conjunctions and other events.

It is likely our first astronomical observations involved our noticing the rising and setting points of the Sun moving to and fro along the horizon during the year, and using them to fix the seasons. The cycle of phases of the Moon gave us our first concept of the mo(o)nth and the beginning of a calendar. From there it would have been very human to look more deeply at the rhythms of the sky and the timing of events like conjunctions and eclipses, and in doing so give birth to what would become astrology and the science of astronomy.

Each year contains about 13 lunar cycles, running from new Moon to the next new Moon. Many peoples around the world named each lunar cycle after some important local event.

Somebody named the current lunar cycle the "Moon of Rising Worms", when worms hibernating deep in the ground wake up and come up to start the new season's work.

If so, the people who named that Moon were certainly not living in Canada.

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• Venus and Jupiter still lie close together, low in the southwest after sunset. Mars lies high in the south.

• The Moon will reach last quarter on March 14.

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

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