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Przekrój
Our science editor delivers news from Earth and space, including the James Webb Space Telescope, the ...
2022-05-15 09:00:00

Cosmic Transmissions (Spring, 2022)

The James Webb Space Telescope. Illustration by NASA (public domain)
Cosmic Transmissions (Spring, 2022)
Cosmic Transmissions (Spring, 2022)
Read in 8 minutes

Gazing through dust

At the very end of 2021, after many grand announcements, the James Webb Space Telescope was launched into space. It is deemed a successor of the Hubble Telescope, but while Hubble is sensitive mainly to visible light and to ultraviolet, Webb will photograph space mostly in infrared.

Scientists picked this particular band of the spectrum for important reasons. Visible light does not penetrate the so-called dark nebulas, of which there are heaps in space, but infrared does. The situation is similar with the clouds of cosmic dust that surround emerging stars and planets. In visible light we can only see the dust, while in infrared we see whatever the dust conceals. This is also the case with the cloud enveloping the centre of the galaxy.

Infrared is also advantageous when using a spectrometer to analyse the composition of the atmosphere of distant planets. Another task that suits this band well is observing the oldest parts of the cosmos. The universe is expanding and its furthest, oldest regions are receding ever more quickly: what follows is that the light waves that reach us from there are getting longer and longer. The light, then, becomes redder and redder, and finally enters the infrared part of the spectrum. So, where Hubble met the limits of its capabilities, Webb will demonstrate its talent for observation, photographing galaxies that came into being over 13 billion years ago at the earliest stages of their development.

As opposed to the Hubble Telescope on its geocentric orbit, the Webb Telescope is located on a heliocentric one, at the L2 libration point – 1.5 million kilometres from Earth. This means that it will always be, to some extent, in the Earth’s shadow, and out of reach of the planet’s thermal radiation. This will protect it from overheating, which is vital for an instrument conducting research in infrared.

This same L2 point is where the William Herschel Telescope used to orbit, bravely serving science; it also worked in infrared, but at its much deeper end. The Webb Telescope can record near infrared and visible light up until the yellow colour – its capabilities overlap with Hubble’s. This is the reason why its creators claim that it is Hubble’s successor (it was also, just like Hubble, made by the American agency NASA, while Herschel originated from the European ESA – so it came from a different dynasty, as it were).


Our Nemesis

Can our planetary system be psychoanalysed? It wouldn’t appear so: after all, there’s no couch huge enough. Still, certain astronomical theories seem to have drawn on psychoanalysis.

In 1984, two groups of researchers independently proposed a hypothesis that the sun has a companion – another object with which it forms a binary star. This hypothetical object – a brown or red dwarf – was named Nemesis, after the Greek goddess of revenge and destiny.

Nemesis would circle the sun once every 26 million years. This would explain the cycles of extinction on Earth, which were pointed out by palaeontologists Jacek Sepkoski and David Raup. The gravity of Nemesis, as it orbits about 1.5 light years away from us, would attract comets to the solar system, and they would then hit bodies like the Earth. Thus the bright sun, surrounded by a merry cluster of chubby planets, would cyclically confront its dark sister, leading her lonely life far away in the cosmic void.

This story might have another layer: extinctions equate not only to death, but also provide an opportunity for the survivors. One such event, 66 million years ago, meant that the era of dinosaurs was succeeded by the time of mammals. We would, then, owe our existence not only to the luminous sun, but also the ruthless Nemesis.

So goes a hypothesis from the 1980s, and it has to be admitted that it has a certain charm from that contrast-loving decade. But some time has passed and one could ask how the idea of Nemesis holds up today. There have been new studies that confirm the cyclical nature of extinctions – every 27 (rather than 26) million years. But as scientists Adrian Melott and Richard Bambach point out, the orbital period of Nemesis, circling at a distance of 1.5 light years, would be at risk of fluctuating so much that the star could not be the culprit of these regular catastrophes. Generally, then, the hypothesis has not been confirmed.

But this does not mean that the sun does not (or did not) have a sister. In 2017, scientists from the University of California and Harvard analysed data about young stars in the Perseus molecular cloud. They found 45 single stars and 55 binary stars, or ones in even more complex arrangements. They also noticed that the younger a star is, the less likely it is to be single. The did some computer modelling based on the results of their observations and found that apparently all stars are born within systems (so, at least as binary stars). Of course, a few dozen systems are not a huge sample, but the results are thought-provoking.

This means that the sun probably also had a sister star. What happened to it? Researchers haven’t determined that yet. They also suggest that we don’t call it Nemesis, but something more friendly. It will be difficult to take that back now, considering that for many years, the star was accused of committing the serial mass murder of whole species. Poor Nemesis.


Magnetizing Mars

All the while, Mars is circling its orbit blithely and can’t even guess at the plans that people have for it. They ponder how to surround it with a magnetic field, so that it becomes more similar to Earth. A magnetic field would protect the planet from solar wind, which is dangerous to living organisms and has a destructive influence on the atmosphere. On Earth, the field is generated by the liquid, hot metal core – Mars doesn’t have one, so a different solution is required.

There are a few ideas. Recently, astrophysicist Brian Koberlein and his team announced that surrounding Mars with a magnetosphere could be done via its moon: Phobos. The satellite orbits its planet at a very small distance (about 6000 kilometres away) and quickly (once every eight hours). Scientists claim that we could spray charged particles from it; after a while, they would surround Mars with a ring providing magnetic protection. The system would be powered by a nuclear reactor.

This is not the only way to ensure Mars has magnetic protection. Other ideas include placing an enormous magnet between the planet and the sun (a vision of such an inflatable cosmic construction was presented in 2017 by Jim Green from NASA). However, Brian Koberlein claims that his method is the simplest and cheapest. While admitting that making the plan a reality is still beyond our technological capabilities, the scientist weaves a wonderful vision of a future Mars, spontaneously transforming under its magnetic aegis. The atmosphere will become denser and, on the poles, the carbon dioxide will melt, which – as it is a greenhouse gas – will raise the temperature. Perhaps water will even flow from its defrosted reservoirs… Unfortunately, the pressure will still be too low for organisms from Earth and there will still be no oxygen, an issue quite pressing not only for humans – plants also need oxygen to live. Alas, it’s impossible to plant trees and fill the atmosphere with oxygen in that way: trees need to breathe and will die without it. So if any being – whether an animal or a plant – was to exist on Mars, it would have to be in an airtight container.

Despite these obvious setbacks, the idea of terraforming Mars, as it is beautifully called, has fervent supporters. They have even designed a flag featuring the colours red, blue and green, which is supposed to symbolize the Red Planet’s evolution into a blue and then a green one, under the enlightened guidance of Homo sapiens. Mars, completely unaware, also already has a hymn (and it’s not “La Marseillaise”). Symbolically, then, it seems ready to accept settlers – but in other ways, not at all.


Bubblians

Who are we? Obviously Earthlings. But perhaps it is worth considering a wider, more general identity? One that would be, as they say, more inclusive? For example: Bubblians! Doesn’t it sound lovely? And proud? If anyone doesn’t know where the word comes from, here’s an explanation.

Space is never completely empty, there’s always some matter to be found – sometimes less, sometimes more. In our galaxy, this amounts to about a million particles per cubic metre. But in this almost-empty space, we can find areas that are even more empty: for example, the Local Bubble, which now contains our solar system.

In the Local Bubble, the density of matter is at least three times lower than that in the surrounding interstellar medium. It is, then, a void within a void. Astronomers discovered it in the 1970s. They also soon worked out how it came to be – it was a result of a series of supernovae explosions about 14 million years ago. Now researchers from the Harvard-Smithsonian Center for Astrophysics claim that they are fairly sure about the number of these explosions, namely 15. They laid waste to the surrounding space, and created areas of dense matter at the edges of the bubble, where new stars are born.

Because the solar system is currently at the very centre of the Local Bubble, we absolutely deserve the moniker of Bubblians. If, for example, an encounter was to take place between humanity and an alien species from a technologically-advanced civilization, we could build Bubblian peace and cooperation on the basis of our shared Bubblian identity, and even try to organize a cyclical song festival called Bubblevision.

We can also safely assume that nobody outside of the Local Bubble is likely to drop in. They’d have to travel for 500 years at the speed of light – an unimaginable feat. On the other hand, the sun – and the Earth with it – won’t be in the Local Bubble forever. Our planet flew into it about five million years ago, and in eight million years it will leave. That will be a difficult moment for us Bubblians. However, we scientists offer some consolation – according to them, bubbles like ours are common in our galaxy and in the universe. Sooner or later, we’ll enter another one.


768 kilometres

This was the length of the longest thunderbolt recorded by researchers; the impressive lightning discharge took place in the south of the United States on 29th April 2020. Less than two months later, on 18th June, in South America, the sky between Argentina and Uruguay was lit by lightning of a record duration: 17.1 seconds. This means that under its light, you could read this note three or four times – or maybe even more, if you’ve done a speed-reading class.

Illustration by Marek Raczkowski
Illustration by Marek Raczkowski

Translated from the Polish by Marta Dziurosz

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