A small, precious handful of dirt

The origins of life

On Oct. 20, 2020, a robot spacecraft took a sample of surface dust from asteroid Bennu. On Sept. 4, 2023, as it passed by the earth en route to asteroid Apophis, it dropped off a capsule carrying that sample. The capsule entered our atmosphere and successfully soft-landed.

The sample was carefully examined under highly sterile conditions, to avoid contamination and was found to contain chemicals important in the creation of life as we know it.

The space mission, known as OSIRIS-APEX, went ahead because the only way to understand how the Solar System came about and what made the appearance of life possible, was to get samples of the raw materials from which the Solar System was made.

Thanks to 4.5 billion years of geological processes, and on our planet billions of years of work by living creatures, none of that primordial material remains on Earth or the other planets. But there was a lot of it in the outer reaches of the Solar System, beyond the orbit of Neptune, left over from the formation of the sun and planets.

However, with the current state of our space technology, that region was very hard and time-consuming to get to. It was better if that material were to come close enough for us to reach it more easily with one of our spacecraft. One other, equally important objective of the project was to see closely how the asteroid was put together, which would help us work out the best way to deal with any asteroid likely to hit our planet.

Our radio telescopes have revealed the great, cold gas and dust clouds between the stars, which contain the raw materials for making new stars and planets, also contain carbon-based molecules that are important in life processes and are the building blocks of life as we know it. However, a lot has to go on to get those chemicals from the clouds to the surfaces or oceans of new planets.

There are a major star and planet nursery visible in the sky at the moment. Find the three stars marking the belt of the constellation of Orion, The Hunter, and scan down from the belt, where his sword would be, That silvery glow is the Orion Nebula, where part of a great cloud of gas and dust is collapsing the form new stars and planets. The nebula is glowing because of the intense radiation from newly born stars.

That shows the first of two problems delivering those seeds of life to new planets. While the star is enjoying its turbulent youth, it gives off lots of ultraviolet light, which can destroy complex molecules. However, the leftover material from star and planet construction, far from the star and relatively safe from the radiation, forms a reservoir of those chemicals.

The second problem is due to the energy released from the in-falling material forming the planet. Young worlds are balls of molten rock; any organic molecules arriving would be destroyed by the heat.

Eventually the star settles down to maturity and ceases to radiate as much ultraviolet radiation, and the planets will have cooled off enough to have solid surfaces and hopefully liquid water oceans. The planets are now ready for those biomolecules.

Occasionally, the asteroids and other bodies containing those organic molecules, orbiting safely far from the star, collide. That can put one or more of them into new paths, taking them inward toward the planets, where they may collide with one of them, delivering a consignment of the seeds of life. No doubt some deliveries happen too early. But eventually some will arrive in the ocean of a young world, starting it on the path to life.

Deliveries continue. There was a big one 65 million years ago in the Gulf of Mexico, and a smaller one in 1908, in Siberia, and others in between.

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• The planetary line-up continues. Saturn lies low in the southwest sunset glow. Moving to the left, (eastward), find brilliant Venus, then Jupiter, almost as bright andfinally Mars, conspicuously red.

• The moon will be full on the 12

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

Planets putting on show as they line up in night sky

The planets are lining up

It is not often that all the planets in the Solar System other than ours are lined up across the night sky for us to see.

The show is in progress now and will climax at the end of February, when Mercury sneaks up through the sunset glow to complete the cast of the show.

Moving outward from the sun, the Solar System's known planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury, Venus, Mars, Jupiter and Saturn are easily visible to the naked eye. Uranus and Neptune need binoculars or a telescope and knowing exactly where to look.

Today’s column focuses on the five that can be found without any optical assistance.

Having all the planets other than ours lined up across the sky is quite rare, but not really scientifically special. Imagine seeing the Solar System from above, with the sun in the middle and all the planets moving around it in concentric circles (or near-circles), in the same direction.

The speed with which they move around their orbits decreases with increasing distance from the sun. All the planets are moving in the same plane, like marbles rolling around on a plate. We live on the third marble out from the centre. In such an arrangement, there will be times that from our position on planet 3, we will see the other bright planets strung out to the left or the right of the sun.

Having the sun on the end of the line means we can have the sun below the horizon, giving us a dark enough sky to see the planets. That happens after sunset, when the planets are to the left of the sun and before sunrise, when the planets are to the right of the sun.

Because Mercury and Venus—being the two planets closest to the sun—can never be far from it as viewed from Earth, start observing soon after sunset, as soon as the stars become visible.

At first sight the planets look like stars, bright point-like objects in the sky. But if you look at them carefully, you will see they shine steadily, whereas the stars twinkle. This is because the stars truly are points of light, whereas the planets are actually tiny discs, as binoculars or a telescope will show.

At the moment, starting in the southwest after sunset, there is Saturn, moderately bright and golden coloured. Next, to the left, is Venus, brilliant white, like an escaped aircraft landing light. Further to the left and higher in the sky is Jupiter, almost as bright and a little bit yellowish. Then there is Mars, less bright than Jupiter and obviously reddish in colour.

All these planets justify getting out the binoculars or better yet, a small telescope. Saturn is surrounded by a system of rings, normally making it the most spectacular planet in the Solar System for anyone with a small telescope. At the moment, we are seeing the rings almost edge-on. Venus appears as a glaringly bright crescent. Jupiter is always worth a look. Binoculars will reveal a tan-coloured disc, with its four largest moons in line with the planet, like beads on a wire.

Mars, the “red planet,” requires a bigger telescope to reveal any of its surface features. However, even with binoculars or a small telescope, it is intriguing to look at that red disc and think about what our spacecraft are telling us about that world, which long ago was so much like ours, and still resembles ours enough to attract intense interest.

In late February, Mercury—the closest planet to the sun—will be far enough to the left of the sun to be above the horizon to be seen against the post-sunset glow. It the sky is clear the planet should be visible as a starlike dot. Binoculars or a small telescope may help, however, only if the sun swell below the horizon.

The only effect this lineup of the planets will have on us is to give us a fantastic opportunity for planet watching. The next lineup will be at the end of February 2048. Then the planets will be lined up to the right of the sun and much lower in the sky so don't waste this opportunity.

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• The moon will reached its first quarter on Feb 5.

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

Al Jabbar and the two giants

Huge doomed stars

Are we living in a black hole?

Galaxy in a black hole?

There is an interesting idea circulating through the astronomical community at the moment.

This is not to say everyone believes it, but there is some evidence supporting it, so it is getting a fair amount of attention. The idea is that we might be living in a black hole.

There are many black holes in our universe. There are those formed in the death throes of giant stars. Massive ones, with masses millions or billions times that of the Sun, sit in the middle of most galaxies, including ours. There are suggestions there could be lots of tiny ones we have not yet detected.

A black hole is the result of the extreme compression of matter. The usual way we see this happening is in the explosion of giant stars at the ends of their lives. The collapse and subsequent explosion compresses the core of the star to the point where it collapses into a black hole.

Any body, whether an asteroid, a moon, a planet or a star, can become a black hole if compressed enough. There will be a point where its gravitational attraction becomes too large to resist. The body will then collapse indefinitely into something extremely small and unbelievably dense.

During that collapse its gravitational attraction grows rapidly, increasingly distorting the fabric of space-time until it forms a bubble shutting off the shrinking body from the rest of the universe. That bubble is known as an “event horizon.”

Things can find their way in, but nothing, not even light, can get out. The body has become a black hole.

The strength of gravity we experience on the surface of the Earth is determined by two things, the diameter of our world and its mass. If our planet was suddenly compressed to half its current diameter, the pull of gravity would be four times larger and we would weigh four times as much.

It is possible, in theory at least, to compress the Earth down to a diameter of a centimetre. At that point the pull of gravity would be ten billion times stronger who than we currently experience. That would be enough to form an event horizon, turning our planet into a black hole.

If we could compress the Sun, it would become a black hole as soon as its diameter fell to three kilometres. Such compression sounds utterly impossible, but we need to remember that matter, as we understand it, is almost totally empty space. There is plenty of emptiness to squeeze out. We can now calculate how much any mass of material has to shrink to become a black hole.

When we look into deep space, we see distant galaxies are receding from us and the farther out we look, the faster they are going. There is theoretically a point where those galaxies would recede at the speed of light and become unobservable. We call what we can see the “Observable” Universe.

Although Einstein's Theory of Relativity states material objects cannot move through space faster than light, a result that has been confirmed in a number of experiments, space-time itself can expand at any speed, carrying the galaxies with it. Imagine a swimmer who can only swim slowly being carried away by fast-moving river.

The current diameter of the Observable Universe is about 93 billion light years, and is estimated to have a total mass of about 6e51 kg (that is six followed by 51 zeroes).

This is where things become really weird. According to the relationship between the masses and sizes of black holes, our universe qualifies as a particularly big black hole.

This idea may or may not be true, but it is a testament to the instruments available to us today that we can even consider such questions.

For years scientists have wondered what the inside of a black hole may be like. Maybe we already know.

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•.After sunset, Venus shines low in the southwest with Saturn close by.

• Jupiter lies high in the southeast and Mars is rising in the northeast.

• The Moon will reach its last quarter Jan. 21 and will be new on Jan. 29.

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