Some see the idea of cutting oneself off from the Sun as irresponsible arrogance, while others see it as cold calculation. But the idea that we can fight global warming by setting up a special mechanism to cool the climate - for example, by building something like a tent for the Earth - is now accepted more calmly in scientific circles than before. According to proponents of geoengineering, we are already changing the climate, but we are acting recklessly. So why don't we start doing this purposefully? Opponents of the idea, however, urge people to come to their senses: global warming has already shown that we know too little about the Earth to try to “re-equip” it without causing unpredictable and, very likely, catastrophic consequences. However, scientists fear that due to processes such as rising sea levels, melting ice and declining crop yields, the debate about geoengineering will not last long. “If any state decides that this kind of project is necessary for them and they have the capacity to implement this project, it is difficult to imagine what could stop them,” says Ken Caldeira, a climate scientist at the Carnegie Institution.
Creating an umbrella of millions of tons of tiny particles in the stratosphere that reflect sunlight could cool the Earth and stop global warming.Caldeira is referring to the simplest and cheapest method of geoengineering: creating an umbrella in the stratosphere from millions of tons of tiny particles (for example, sulfuric acid salts) that reflect sunlight. The material can be delivered using airplanes, balloons or guns of warships. There is no doubt that in this way it will be possible to cool the Earth - nature itself has set an example. In 1991, Mount Pinatubo erupted in the Philippines, releasing 10 million tons of sulfur into the stratosphere. An obscuring haze spread across the planet, and for a year the average temperature dropped by about 0.6°C. Scientists have created a similar model, but much smaller in volume. True, the particles will gradually fall to the ground, so that every year more and more new portions of sulfur particles will have to be sent into the stratosphere. Not so with a project proposed by Roger Angel, a distinguished astronomer and telescope designer at the University of Arizona. Angel proposed bringing trillions of the thinnest silicon nitride disks into space between the Earth and the Sun, reflecting sunlight. Each such reflector, weighing less than a gram, is an autonomously operating robot. According to Angela's calculations, the implementation of his plan will take decades and cost trillions of dollars. In such a period and with such funding, it is possible to free ourselves from fuel dependence and solve the problem of global warming - and this is much more important. If we build a shield without reducing our carbon emissions, and then something goes wrong with our design, the consequences will be dire: global warming, which is what this whole thing is all about, will hit us with full force. This may be the worst unintended consequence of geoengineering - but not the only one: who knows if the ozone layer will be damaged or droughts will become more frequent? However, if the level of CO2 in the atmosphere continues to rise, we risk facing very serious problems that will have to be resolved quickly. And then, perhaps, we will be happy with any decision, even a very controversial one.
> Variable stars
Consider variable stars: description of the star class, why they can change brightness, duration of change in magnitude, solar fluctuations, types of variables.
Variable called star, if it is capable of changing brightness. That is, its apparent magnitude, for some reason, periodically changes for an earthly observer. Such changes can take years, sometimes only seconds, and range between 1/1000th of a magnitude and 20th.
Among the representatives of variable stars, more than 100,000 celestial bodies were included in the catalogs, and thousands more act as suspicious variables. is also a variable whose luminosity fluctuates by 1/1000th of a magnitude and whose period spans 11 years.
History of Variable Stars
The history of the study of variable stars begins with Omicron Ceti (Mira). David Fabricius described it as new in 1596. In 1638, Johannes Hogvalds noticed its pulsation for 11 months. This was a valuable discovery, as it suggested that the stars were not something eternal (as Aristotle claimed). Supernovae and variables helped usher in a new era of astronomy.
After this, only in one century it was possible to find 4 variables of the World type. It turned out that they were known about before appearing in the records of the Western world. For example, three were listed in the documents of Ancient China and Korea.
In 1669, the variable eclipsing star Algol was discovered, although its variability was only explained by John Goodrick in 1784. The third is Chi Swan, found in 1686 and 1704. Over the next 80 years, 7 more were found.
Since 1850, a boom in the search for variables began, because photography was actively developing. Just so you understand, since 2008 there have been more than 46,000 variables alone.
Characteristics and composition of variable stars
Variability has reasons. This applies to changes in luminosity or mass, as well as some obstacles that prevent light from reaching. Therefore, types of variable stars are distinguished. Pulsating variable stars inflate and contract. Double eclipses lose brightness when one of them overlaps the other. Some variables represent two nearby stars exchanging mass.
Two main types of variable stars can be distinguished. There are internal variables - their brightness changes due to pulsation, change in size or eruption. And there are external ones - the reason lies in the eclipse that occurs due to mutual rotation.
Internal variable stars
Cepheids- incredibly bright stars, exceeding solar luminosity by 500-300,000 times. Frequency – 1-100 days. This is a pulsating type, capable of rapidly expanding and contracting in a short period of time. These are valuable objects, since they are used to measure distances to other celestial bodies and formations.
Other pulsating variables include RR Lyrae, which has a much shorter period and is older. There are RV Taurus - supergiants with noticeable wobble. If we look at stars with a long period, then these are objects like Mira - cold red supergiants. Semi-regular - red giants or supergiants, whose periodicity takes 30-1000 days. One of the most popular is .
Don't forget about the Cepheid variable V1, which has made its mark in the history of the study of the Universe. It was with her help that Edwin Hubble realized that the nebula in which it was located was a galaxy. This means that space is not limited to the Milky Way.
Cataclysmic variables (“explosives”) glow due to sudden or very powerful flashes created by thermonuclear processes. Among them are novae, supernovae and dwarf novae.
Supernovae- are dynamic. The amount of energy emitted sometimes exceeds the capabilities of the entire galaxy. They can grow to magnitude 20, becoming 100 million times brighter. Most often, they are formed at the moment of death of a massive star, although after this a core (neutron star) may remain or a planetary nebula may form.
For example, V1280 Scorpii reached its maximum brightness in 2007. Over the past 70 years, Nova Cygnus has been the brightest. Everyone was also amazed by V603 Orla, which exploded in 1901. During 1918, it was no less bright.
Dwarf novae are double white stars that transfer mass and produce regular outbursts. There are symbiotic variables - close binary systems, in which a red giant and a hot blue star appear.
Eruptions are noticeable by eruptive variables capable of interacting with other substances. There are a lot of subtypes: flaring stars, supergiants, protostars, Orion variables. Some of them act as binary systems.
External variable stars
TO eclipsing refer to stars that periodically block each other's light in observation. Each of them may have its own planets, repeating the eclipse mechanism that occurs in. Algol is such an object. NASA's Kepler mission managed to find more than 2,600 eclipsing binary stars during its mission.
Rotating are variables that exhibit small variations in light created by surface spots. Very often these are double systems formed in the form of ellipses, which causes changes in brightness during movement.
Pulsars- rotating neutron stars that produce electromagnetic radiation that can only be seen if it is directed towards us. Light intervals can be measured and tracked because they are precise. Very often they are called space beacons. If a pulsar rotates very quickly, it loses a huge amount of mass per second. They are called millisecond pulsars. The fastest representative is capable of making 43,000 revolutions in a minute. Their speed is explained by gravitational connection with ordinary stars. During such contact, the gas moves from normal to pulsar, accelerating its rotation.
Future research on variable stars
It is important to understand that these celestial bodies are extremely useful to astronomers, as they allow them to understand the radii, mass, temperature and visibility of other stars. In addition, they help to penetrate the composition and study the evolutionary path. But studying them is a painstaking and lengthy process, for which not only special instruments are used, but also amateur telescopes.
Some variables are especially important, such as Cepheids. They help determine the age of the entire Universe and reveal the secrets of distant galaxies. Variables of the World reveal the secrets of our Sun. Supernovae reveal a lot about the expansion process. The cataclysmic ones contain information about active galaxies and supermassive black holes. Therefore, variable stars can explain why some things in the Universe are not stable.
The supermassive black hole Sgr A* is quite possibly a remnant of a once active and powerful galactic nucleus. As is known, at the early stage of its formation, the Universe was simply incinerated by the active nuclei of many galaxies (AGN). They were all active nuclei that were powered by supermassive black holes. The amazing fact is that at that time most of them could easily outshine any other simple galaxy; if they existed today, their light could be seen across the entire Universe, which is billions and billions of light years (today's most distant galaxy , discovered by telescopes is located at a distance of 13.2 billion years).
Supermassive black hole at the center of the Milky Way
Although the supermassive black hole Sgr A* is most likely dormant, new evidence obtained by astrophysicists suggests that it was also previously an active galactic nucleus. The first hint of the formation of this theory appeared about two years ago. At that time, astronomers discovered Fermi bubbles - massive lobes of radiation with extremely high energy levels. All of them extend over a distance of 30 thousand light years both north and south of the galactic center.
Rice. 1 Sagittarius A* (center) and two light echoes from a recent explosion (circled)
Of course, what is the source of these bubbles is a hot topic today. Some astrophysicists believe they are filled with powerful star formation in the disk, while others believe they may be filled with a powerful jet from the supermassive black hole Sgr A*. Today, it is becoming more and more likely that the Fermi bubbles were created quite recently by a powerful jet protruding from the center of the galaxy.
Rice. 2 Graphical visualization of Fermi bubbles detected by the gamma-ray telescope 
All this clearly demonstrates that they are in fact remnants of a much more distant past.
The Magellanic Stream is further evidence of recent galactic activity
Recently, astronomers from the Sydney Institute of Astronomy (Australia) discovered new evidence that links the Milky Way's supermassive black hole to a modern active galactic nucleus. As you know, the Magellanic Stream is a long ribbon that extends almost halfway around our galaxy and stretches all the way to two small companion galaxies of the Milky Way.
Rice. 3 Magellanic Stream (note the red color)
This Magellanic Stream is likely another ancient remnant of ancient galactic activity. If we assume that Sgr A* was once very bright and active, it could easily illuminate the entire Magellanic Stream, causing the atoms to absorb energy from the incoming light at an ever faster rate. This effect is still visible after many millions of years, as stated by experts in the “Science News” section of the “Stock Leader” publication for investors.
SUKHUM, December 13 – Sputnik. The most beautiful starfall in the northern hemisphere of the Earth - the Geminids - will outshine the light of the full Moon (Supermoon) on the night of December 14, the Moscow Planetarium said in a statement.
Every year, from December 4 to 17, one of the richest and most beautiful meteor showers in the northern hemisphere of the Earth - the Geminids - is observed in the night sky. This phenomenon occurs because planet Earth in December passes through a swarm of small particles thrown into space by the asteroid Phaeton. The stream does not fly towards the Earth, but catches up with it, therefore the speed of the meteors is low - about 35 km/s. At the peak of Geminid activity, up to hundreds of meteors can be observed per hour.
“The maximum activity of the Geminids occurs on December 14, 2016 at 3.00 Moscow time, a fall of up to 120 meteors per hour is expected. But the Moon that night will be at perigee (at its closest distance from the Earth) and at 3.06 Moscow time will enter the full moon phase - the third will occur is considered to be the supermoon of the year, and this will make observing meteors very unfavorable. The light of the full moon will be so bright that it will almost completely eclipse the “starfall”. If the weather is cloudless, only the brightest meteors will be visible - not very fast, bright and practically non-existent. meteors with traces of white color,” the message notes.
Unlike most other meteor showers, the Geminids' progenitor is not a comet, but an object discovered in 1983 using an infrared space telescope and named 3200 Phaethon.
It is not a comet, as it has neither a coma nor a tail. Astronomers classify it as an intermediate object, which is a cross between asteroids and comets. Phaeton's orbit is very elongated, which allows it, during its movement around the Sun, to cross the orbits of all four terrestrial planets from Mercury to Mars. Interestingly, at the same time, it comes closer to the Sun than any other known asteroid (the record belongs to asteroid 2006 HY51), which is why it was named after the hero of the Greek myth about Phaeton, the son of the Sun god Helios.
Every 1.5 years, Phaeton approaches the Sun at a distance that is more than twice the perihelion of the planet Mercury, while the speed of Phaeton near the Sun can reach almost 200 km/s (720,000 km/h). Studies of the meteor shower have shown that its meteor particles are about 1000 years old. That is, if Phaethon was a comet, then over 1000 years it made many revolutions around the Sun, as a result of which all the ice from its core evaporated, and the comet’s tail was gone, only a stone skeleton remained from the core.
The Geminids got their name from the name of the constellation Gemini, in which the radiant of the shower is located (the area where meteors are released). The Geminid radiant is located near the bright star Castor. The meteor shower in the constellation Gemini was discovered at the end of the 20th century. The Geminids are a beautiful giant meteor shower that outnumbers all other meteor showers in terms of shooting stars, including the August Perseids.
29 March 2006 23:00...At night it illuminates the earth!” It's all about her, about the Moon, which hid the Sun for short but memorable minutes. Indeed, many people poured out onto the streets of the city to admire this rare celestial phenomenon. Several hundred people gathered on Lenin Square, mostly young people and children riding skateboards and bikes. The sun was half hidden in the moon's shadow, and suddenly it became noticeably colder. And a strange twilight slowly set in: it didn’t seem like evening, but the light had noticeably dimmed... And the sounds were muffled, and everything around became unreal, not as always. And what was left of the sun was a tiny horn, a kind of strongly “bitten” crescent.
The people armed themselves as best they could: someone looked at the eclipse through exposed film, through “welding” glasses (we even saw a welding mask: cumbersome, but spectacular). The natural color of the remnant of the solar disk was given by compact discs folded in half. The sun horn looked blood red through the floppy disk window. But the doctors from the nearest clinic especially amused the people: they poured out into the street and used X-rays for viewing! And they looked at the sun, and examined the fractures properly: two in one! And there were those who hastily smoked the glass of their own glasses with gasoline lighters and matches. And everyone was occupied with one question: “Will it hide it completely or not? So what, what did they write about incomplete? What if it’s completely?..”
The action was short-lived, about half an hour. And when the eclipse reached its maximum, the Moon seemed to spin in place, revealing first the upper part of the edge of the Sun, then the lower. Here the horn hangs with its ends down, now it has turned, and now it has become like the usual crescent. And that’s it, the moon’s shadow went its way, the sun began to slowly free itself from the shadow. And everything returned: warmth, light, conversations became louder, cell phones started working, which suddenly malfunctioned.
The sun has returned.
Photo by Yuri Rubinsky.
