The most interesting about our solar system, galaxy and universe

: Miscellanea

In this article, we will give answers to the most common questions of mankind about our solar system, galaxy and universe.

The most interesting about our solar system, galaxy and universe — stock.adobe.com

In this article, we will give answers to the most common questions of mankind about our solar system, galaxy and universe. But first, let's look at the difference between these concepts.

The solar system is a planetary system that includes the central star – the Sun, and all natural space objects (planets, asteroids, comets), united by gravitational interaction.

A galaxy is a gravitationally bound system of stars, star clusters, interstellar gas and dust, dark matter, and planets. Our solar system is part of the Milky Way galaxy.

The Universe is everything that physically exists, the totality of space, time and the most diverse forms of matter, such as planets, stars, galaxies and components of intergalactic space. The universe is so big that its size is hard to imagine and no one knows how big it is.

Which planet in the solar system is the hottest?

The hottest planet in the solar system is Venus. The average temperature on its surface is about 470 degrees Celsius. Although Mercury is closer to the Sun, it does not have an atmosphere, and the heat from its surface heated by the Sun is freely radiated into the surrounding outer space. Venus, on the other hand, has a dense atmosphere that retains heat through a powerful greenhouse effect.

Which planet in the solar system has the largest mountains and which has the deepest depressions?

In both of these "nominations" the record holder in the solar system is Mars. On this planet is the largest mountain in the solar system – the extinct volcano Olympus. It has a height of about 27 kilometers and a width at the base of 520 kilometers.

Here is also the deepest depression – the Valis Marineris canyon system. In length, it stretches for almost 4000 kilometers, and its depth is from 2 to 7 kilometers.

Which planets in the solar system have rings and what do these rings consist of?

Today it is known that all four gaseous giants have rings: Jupiter, Saturn, Uranus and Neptune. Saturn has the most beautiful and visible rings. These formations consist of many solid (ice) bodies reflecting sunlight, ranging in size from a grain of sand to 20-30 meters.

Despite the impressive appearance of the rings, the amount of matter that makes them up is extremely small. If we collect all the substance of the rings of Saturn into one spherical monolith, the diameter of this monolith will not exceed 100 kilometers.

In which month is the Earth closest to the Sun and in which month is it farthest from it?

The point in the orbit of any planet closest to the Sun is called perihelion, and the farthest point is called aphelion. In the present epoch, our planet passes through perihelion on January 2–5, and through aphelion on July 1–5.

By the way, many are surprised to learn that the Earth is closest to the luminary in January, and farthest from it – in July. But only residents of the Northern Hemisphere, where January is the middle of winter, can be surprised. In the Southern Hemisphere, where only 10% of the world's population lives, this fact is unlikely to surprise anyone, because the middle of winter here is July.

But the change of seasons (spring, summer, autumn, winter) does not happen at all because the Earth either approaches the Sun or moves away from it. And yet, many people still think so.

The main reason for the change of seasons is the tilt of the earth's axis, and not the remoteness of our planet from the Sun.

The fact is that the Earth, in addition to rotating around the Sun, rotates around an imaginary axis (a line passing through the North and South Poles). If the Earth's axis were at right angles to the plane of its orbit, we would have no seasons, and all days would be the same. Without axial tilt, the length of day and night would be the same anywhere on the Earth, and during the day the Sun would occupy a position above the horizon at the same height throughout the year.

But the Earth's axis of rotation is tilted 23,44° relative to the perpendicular to its orbital plane. This causes seasonal changes on the surface of our planet with a period of one tropical year – 365,24 solar days.

Why are there no seasons on Mercury?

The axis of Mercury's own rotation is almost perpendicular to the plane of its orbit, and therefore there are no seasons on it in the sense that we put into this concept on Earth. The sun's rays fall on the polar regions of the planet almost horizontally, and eternal winter reigns in them (there is no complete darkness at the poles only because the Sun is much larger than Mercury).

Mercury is the closest planet to our hot star. However, the results of studies of Mercury suggest that there are glaciers at its poles (the glacial layer can reach two meters and is covered with a layer of dust).

What is the size and age of the largest meteorite crater on the Earth's surface?

The largest of all the craters in which the remains of meteorite material were found is the Barringer Crater in Arizona, USA. It is a well-preserved depression with a diameter of about 1200 meters and a depth of about 200 meters.

Its edges rise about 50 meters above the surrounding plain. It is believed that since the formation of the crater, the edge has lost 15–20 meters of height on the crest of the edge as a result of natural erosion.

The crater arose about 50,000 years ago after the fall of a 50-meter meteorite weighing 300,000 tons and flying at a speed of about 50,000 km/h. The explosion from the fall was similar in power to the explosion of 8000 atomic bombs similar to those dropped on Hiroshima.

Thanks to its good preservation, this crater is one of the most famous on Earth. He is often filmed in scientific documentaries, in particular by Discovery and the BBC. Arizona Crater is one of the landmarks of the state of Arizona. It is visited by many tourists every day.

There is a museum on the edge of the crater, the official booklet of which states the following:

“While there are larger scale impact marks on Earth, this crater was the first to be proven to be of meteoric origin and is the best preserved of its original appearance.”

Barringer Crater was recognized as the most lunar landscape on Earth, and it was there that all the astronauts who were to go on a flight to the Moon underwent part of the training.

What is the size of the largest known meteorite crater in the solar system, and where is it located?

The largest known meteorite crater, Valhalla, is located on Jupiter's moon Callisto. It has a bright central region about 600 kilometers in diameter and a system of concentric ridges extending 1500 kilometers from the center of the crater.

How dangerous are asteroids?

The asteroid hazard scale, adopted by the International Astronomical Union, is graduated from 0 to 10 points. Zero gets an asteroid whose orbit intersects with the Earth's orbit, but it has no chance of a collision. Ten marks an asteroid, the fall of which can lead to a global climate catastrophe.

Among the approximately 2000 asteroids with a diameter of more than a kilometer, crossing the Earth's orbit, all are "null".

Why is the night sky dark?

If the universe were infinite in space and time, then in any direction there would be some star on the line of sight. The entire surface of the night sky would have to appear dazzlingly bright, like the surface of the sun. The contradiction of this statement with what we observe in reality is called the Olbers paradox (or the Szezo-Olbers paradox).

Olbers' paradox, also known as the dark night sky paradox, is an argument in astrophysics and physical cosmology that the darkness of the night sky contradicts the assumption of an infinite and eternal static universe. The darkness of the night sky is one of the evidence for a dynamic universe such as the Big Bang model.

This paradox cannot be explained within the framework of the theory of the stationary Universe. However, it is easy to eliminate, given that the universe began as a result of the so-called Big Bang and that its age is "only" 13,7 billion years. The most distant objects that we can see are no more than 13,7 billion light-years away from us, and the light from more distant objects to us simply has not yet managed to reach us (the speed of light, as you know, is not infinite and is 300,000 kilometers per second). That's why the night sky is dark.

Which star is the brightest?

The brightest star in the night sky is Alpha Canis Major, better known as Sirius (Greek for sparkling). This star is observable from any region of the Earth, with the exception of its northernmost regions. It is located at a distance of 8,6 light years from the solar system and is one of the closest stars to Earth.

The diameter of Sirius is almost twice that of the sun, its mass is 2,35 of the mass of our star, the temperature on its surface is about 10,000 degrees Kelvin (on the visible surface of the Sun, it is approximately 6000 kelvins). At the same time, the luminosity of Sirius is 25 times greater than the solar one.

Due to the relative proximity of Sirius to us, its movement in the celestial sphere is much more noticeable than that of other stars: over the past 2000 years, it has changed its position in the sky by approximately 44 arc minutes, which is one and a half diameters of the moon on a full moon. In its movement in the direction of the observer's line of sight, Sirius is approaching us at a speed of about 8 kilometers per second.

Sirius is a binary star, the second component of which is a white dwarf known as Sirius B. It has a much lower luminosity, and therefore is difficult to distinguish next to the radiance of Sirius itself.

How many stars are there in the universe?

In 2004, Australian astronomers counted all the stars in the visible universe. To do this, they chose a random square of the sky, measured its brightness, recalculated it from the brightness of the average star to the number of stars, and extended the result to the entire celestial sphere. In total, we got 70 sextillion (7 with 22 zeros) stars. This is 10 times more than the number of grains of sand in all the deserts and on all the beaches of the Earth.

How big is the age of the Universe and on the basis of what data is it determined?

In 2003, with the help of a space probe launched by NASA (US National Aeronautics and Space Administration), equipped with special equipment, measurements of the temperature of the background microwave (relict) radiation were carried out with an accuracy of a millionth of a degree. The results of these measurements made it possible to establish that the age of the Universe is 13,7 billion years and that the formation of the first generation of stars began 200 million years after the Big Bang.

How big is our galaxy?

Our Galaxy (the Milky Way) has a complex shape, in the first approximation it can be compared with a giant lentil (lens).

The vast majority of galactic matter (stars, interstellar gas, dust) occupies a lenticular volume about 100,000 light-years across and about 12000 light-years thick in the central part. Another (significantly smaller) part of the galactic matter fills an almost spherical volume with a radius of about 50,000 light years. The centers of the lenticular and spherical components of the Galaxy coincide.