Astronomy, the role of various stars

Mars is the fourth farthest from the sun and the seventh largest planet in the solar system;

Basic parameters of Mars:

Half-length diameter of orbit: 227.94 million kilometers (1.52 astronomical unit)

Period of revolution: 686.98 days.

Average orbital speed: 24.13km/s.

Track eccentricity: 0.093

Track inclination: 1.8 degrees.

Earth's equatorial radius: 3398 kilometers

Mass (Earth mass = 1): 0. 1074.

Density: 3.94 g/cm3

Rotation period: 1.026 days.

Number of satellites: 2

Orbit: 227,940,000 kilometers (65,438+0.52 astronomical units) from the sun.

Mars (Greek: Ares) is called the God of War. This may be due to its bright red color; Mars is sometimes called the "red planet". Interesting note: Before the Greeks, the ancient Romans once worshipped Mars as the god of farming. Aggressive Greeks regard Mars as a symbol of war) and the name "March" also comes from Mars.

Humans have known about Mars since prehistoric times. Because it is considered to be the best place for human beings to live in the solar system (except the earth), it is loved by science fiction writers. But it is a pity that Lowell "saw" the famous "Canal" and other things, just like the princesses of Barsoumian, are all fictitious.

The first exploration of Mars was carried out by Mariner 4 in 1965. Several attempts were made, including two Viking planes (left) in 1976. Then, after a lapse of 20 years,1July 4, 997, the Mars Pathfinder finally landed on Mars (right).

The orbit of Mars is very elliptical. Therefore, where the sun shines, the temperature difference between perihelion and aphelion is nearly 30 degrees Celsius. This has a great influence on the climate of Mars. The average temperature on Mars is about 2 18K(-55℃, -67F), but it has a span from 140K(- 133℃, -207F) in winter to nearly 300K(27℃, 80F) in summer. Although Mars is much smaller than the earth, its surface area is equivalent to the land area of the earth's surface.

Besides the earth, Mars is a solid surface planet with the most interesting terrain. There are some spectacular terrains here:

-Mount Olympus: It is 24 kilometers (78,000 feet) from the earth's surface and is the largest mountain range in the solar system. Its base is more than 500 kilometers in diameter and is surrounded by cliffs as high as 6 kilometers (20,000 feet) (right);

-Tharsis: a huge bulge on the surface of Mars, with a width of about 4,000 kilometers and a height of 10 kilometers;

Valles Marineris: a group of canyons with a depth of 2 to 7 kilometers and a length of 4,000 kilometers (the title is as follows);

-Hellas Planitia: an impact crater with a depth of over 6,000 meters and a diameter of 2,000 kilometers in the southern hemisphere.

There are many ancient craters on the surface of Mars. But there are also many newly formed valleys, ridges, hills and plains.

In the southern hemisphere of Mars, there is a curved circular highland similar to that on the moon (left). On the contrary, most of its northern hemisphere consists of newly formed low-level plains. The formation process of these plains is very complicated. There is a huge height change of several kilometers on the north-south border. The reasons for the huge difference between the North and the South and the drastic changes in the border areas are still unknown (some people speculate that this is due to the huge force generated by the increase of extraterrestrial objects). Recently, some scientists began to wonder whether those steep mountains were in their original places. This question will be answered by the "Mars Global Explorer".

The internal situation of Mars is inferred only from its surface information and a large number of related data. It is generally believed that its core is composed of high-density substances with a radius of 1700 km; Wrapped in a layer of lava, thicker than the earth's mantle; The outermost layer is a thin shell. Compared with other solid planets, the density of Mars is lower, which indicates that the iron (magnesium and iron sulfide) in the core of Mars may contain more sulfur.

Like Mercury and the Moon, Mars lacks active plate movements; There is no indication that there has been crustal translation on Mars, which can cause mountains with as many folds as the earth. Because there is no lateral movement, the giant hot zone under the crust is stationary relative to the ground. Coupled with the slight gravity on the ground, it led to the Taris uplift and huge volcano. However, no signs of volcanic activity have been found recently. Although Mars may have had many volcanic movements, it seems that there has never been any plate movement.

There have been floods on Mars and some small rivers on the ground (right), which clearly proves that many places have been eroded. In the past, there was clean water on the surface of Mars, and there might even be great lakes and oceans. But these things seem to have only existed for a short time, estimated to be around 4 billion years ago. (barres Maneri was not formed by running water. It is caused by the extension and impact of shells, accompanied by Tarsis uplift).

In the early days of Mars, it was very similar to Earth. Like the earth, almost all the carbon dioxide on Mars has been converted into carbonaceous rocks. However, due to the lack of plate movement of the earth, Mars can't recycle carbon dioxide into its atmosphere again, so it can't produce significant greenhouse effect. Therefore, even if it is pulled to the same distance from the sun as the earth, the temperature on the surface of Mars is still much colder than the earth.

The thin atmosphere of Mars is mainly composed of carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%), trace oxygen (0. 15%) and water vapor (0.03%). The average atmospheric pressure on the surface of Mars is only about 7 millibar (less than 1% on the earth), but it changes with the height, reaching 9 millibar in the deepest part of the basin and only 1 millibar at the top of Olympus. But it is enough to support hurricanes and big storms that occasionally sweep the whole earth. Although the thin atmosphere of Mars will also produce greenhouse effect, these can only raise its surface temperature by 5K, which is far lower than the temperature of Venus and the Earth as we know it.

The poles of Mars are permanently covered with solid carbon dioxide (dry ice). The structure of this ice sheet is layered, which is formed by the alternating overlapping of ice layers and the change of carbon dioxide layers. In the summer in the north, carbon dioxide is completely sublimated, and the rest is the ice water layer. Since the carbon dioxide in the south has never completely disappeared, we can't know whether there is ice under the ice in the south (left). The reason for this phenomenon is unknown, but it may be that the long-term change of the angle between the equatorial plane of Mars and its orbit leads to climate change. Maybe there is water deeper under the surface of Mars. This change in polar cover caused by seasonal changes has changed the pressure on Mars by about 25% (measured by Viking).

However, recent observations through the Hubble telescope show that Viking's environment at that time was not typical. The atmosphere of Mars now seems colder and drier than that detected by Viking (see STScI website for details).

Viking tried to do an experiment to determine whether there is life on Mars, but the result was negative. But optimists point out that only two samples are qualified, and they are not from the best place. Future Mars explorers will continue to do more experiments.

A small meteorite (SNC meteorite) is thought to come from Mars.

1August 6, 996, David? David Mackay and others claimed that organic matter was first found in Martian meteorites. The author even said that this ingredient, together with some other minerals obtained from meteorites, can be a proof of the existence of ancient microorganisms on Mars. (left? )

Such an amazing conclusion does not lead to the conclusion that aliens exist. Think of yourself as David? After Zhu put forward his views, some opponents' studies were also published. But any conclusion should be "reasonable and well-founded". There are many things to be done before the conclusion is announced with complete certainty.

There is a large area of weak gravity in the tropical region of Mars. This is an unexpected discovery when the global Mars probe entered the orbit of Mars. They may have been left behind when early shells disappeared. This may be very useful for studying the internal structure of Mars, past atmospheric pressure and even the possibility of ancient life.

Mars is easy to see with the naked eye in the night sky. Because it is close to the earth, it looks very bright. Mike. Harvey's planet search map shows the positions of Mars and other planets in the sky. More and more details and better charts will be discovered and completed by astronomical programs such as Starlight.

mercury

English name: Mercury

Mercury, the closest to the sun, is the second asteroid in the solar system. Mercury is smaller in diameter than Ganymede and Titan, but it is heavier.

Basic parameters of mercury:

Half-length diameter of orbit: 57,965,438+00,000 kilometers (0.38 astronomical unit)

Period of revolution: 87.70 days.

Average orbital speed: 47.89 km/s.

Track eccentricity: 0.206

Track inclination: 7.0 degrees

Planet equatorial radius: 2440 km

Mass (Earth mass = 1): 0.0553

Density: 5.43g/cm3

Rotation period: 58.65 days

Number of satellites: None

Orbit: 57,965,438+00,000 kilometers (0.38 astronomical unit) from the sun.

In ancient Roman mythology, Mercury was the god of commerce, travel and theft, that is, Hermes in ancient Greek mythology, the god who sent letters to the gods. Perhaps it is because Mercury moves rapidly in the air, so it is named.

Mercury was discovered as early as 3000 BC in Sumerian times, and the ancient Greeks gave it two names: Apollo when it first appeared in the morning and Hermes shining in the night sky. However, ancient Greek astronomers knew that these two names actually refer to the same star, and Heraclitus (a Greek philosopher in the 5th century BC) even thought that Mercury and Venus revolved around the sun instead of the earth.

Only mariner 10 visited Mercury three times in 1973 and 1974. It only surveyed 45% of the surface of Mercury (unfortunately, Mercury is too close to the sun for Hubble to photograph safely).

Mercury's orbit deviates from the perfect circle to a great extent. The closest point is only 46 million kilometers away from the sun, but the apohelion is 70 million kilometers away. At the perihelion of the orbit, according to precession (precession: precession of the earth's axis causes vernal equinox to slowly move westward at a speed of 0.2 "per year, making the tropical year shorter than the sidereal year), it moves around the sun at a very slow speed. There are two kinds of precession: solar precession and planetary precession. The latter is the change of ecliptic plane caused by planetary gravity. ) In the19th century, astronomers observed the orbital radius of Mercury very carefully, but they could not explain it properly with Newtonian mechanics. The subtle difference between the actual observed value and the predicted value is a small problem (one seventh of a degree per thousand years), but it has been puzzling astronomers for decades. Some people think that there is another planet in the orbit near Mercury (sometimes called Vulcan, or "wishing star"), which explains this difference. As a result, the final answer is quite dramatic: Einstein's general theory of relativity. In the early days when people accepted this theory, the correct prediction of mercury's motion was a very important factor. Mercury revolves around the sun because its gravitational field is extremely huge. According to the general theory of relativity, mass produces a gravitational field, which can be regarded as mass, so the giant gravitational field can be regarded as mass, which produces a small force field and makes its orbit deviate. Similar to the divergence of electromagnetic waves, the changing magnetic field generates an electric field, and the changing electric field generates a magnetic field, which is transmitted to a distance. -translation notes)

Before 1962, people always thought that the time of Mercury's rotation was the same as that of its revolution, so the side facing the sun was unchanged. This is similar to the fact that the moon always faces the earth with the same half face. However, at 1965, it was found that this theory was wrong through the observation of Doppler radar. Now we know that mercury rotates three times while turning two times. Mercury is the only celestial body in the solar system whose period of revolution to rotation period ratio is not 1: 1.

Because of the above situation and the extreme deviation of Mercury's orbit from the perfect circle, the observers on Mercury will see a very strange scene. Observers at some longitudes will see that when the sun rises, it will gradually increase obviously as it moves slowly to the zenith. The sun will stop at the zenith, stop again after a short retrogression, and then continue to travel to the horizon, while shrinking obviously. During this time, the stars will cross the sky at three times the speed. Observers at other locations on the surface of Mercury will see different but equally unusual celestial movements.

The temperature difference on Mercury is the largest in the whole solar system, ranging from 90 to 700. In contrast, the temperature of Venus is slightly higher, but it is more stable.

Mercury is similar to the moon in many ways. There are many craters on its surface, which is very old. It also has no plate movement. On the other hand, the density of mercury is much larger than that of the moon (5.43g/cm3 for mercury and 3.34g/cm3 for the moon). Mercury is the second largest celestial body in the solar system in density after the earth. In fact, the high density of the earth is partly due to the compression of gravity; Otherwise, the density of Mercury will be greater than that of the Earth, indicating that the iron core of Mercury is relatively larger than that of the Earth, and it is likely to constitute most of the planets. So relatively speaking, Mercury has only a thin silicate mantle and crust.

The huge iron core has a radius of 1800 to 1900 km, and is the dominator inside Mercury. The silicate shell is only 500 to 600 kilometers thick, and at least part of the inner core may be molten.

In fact, Mercury's atmosphere is very thin, made up of destroyed atoms brought by the solar wind. The temperature of mercury is so high that these atoms quickly escape into space, so compared with the stable atmosphere of the earth and Venus, the atmosphere of mercury is frequently replaced.

The surface of Mercury presents huge steep slopes, some of which are hundreds of kilometers long and as high as three kilometers. Some cross the outer ring of the crater, while others are compressed by steep slopes. It is estimated that the surface of Mercury has shrunk by about 0. 1% (or by about 1 km in the radius of the planet).

One of the largest landforms on Mercury is the Callaris Basin (right), with a diameter of about 1300 km, which is considered to be similar to Maria, the largest basin on the moon. Like the moon's basin, the Carolis basin was probably formed in the early collision of the solar system, which probably caused the strange terrain that the other side of the planet faced the basin at the same time (left).

In addition to the terrain covered with craters, Mercury has relatively flat plains, some of which may be the result of ancient volcanic movements, but others are probably the result of the deposition of ejecta formed by meteorites.

The data from Mariner provides some preliminary signs of recent volcanic activity on Mercury, but we need more information to confirm it.

Surprisingly, the radar scanning of Mercury's North Pole (the unexplored area of Mariner 10) shows signs of ice in some well-protected craters.

Mercury's magnetic field is very small, and its magnetic field intensity is about 1% of that of the earth.

So far, mercury has not been found to have satellites.

Mercury can usually be observed through binoculars or even directly with the naked eye, but it is always close to the sun and it is difficult to see in the twilight. Mike Harvey's planet-finding map points out the position of Mercury in the sky (and the positions of other planets) at this time, and then it is more and more carefully customized by the astronomical program "Starry".

Venus

English name: Venus

One of the eight planets, China called it Taibai or Taibai Venus in ancient times. It is sometimes the morning star, which appears in the eastern sky before dawn and is called "Qi Ming". Sometimes it is a dim star, which appears in the western sky after dusk and is called Chang Gung. Venus is the brightest star in the whole day except the sun and the moon, just like a dazzling diamond, so the ancient Greeks called it Aphrodite, the goddess of love and beauty, while the Romans called it Venus, the god of beauty.

Venus basic parameters

Period of revolution: 224.70438+0 days.

Average orbital speed: 35.03 km/s.

Track eccentricity: 0.007

Track inclination: 3.4 degrees

Equatorial diameter: 12,103.6km.

Mass (Earth mass = 1): 0.8 150.

Density: 5.24 g/cm3

Rotation period: 243.0 1 day.

Number of satellites: 0

Radius of revolution:108,208,930 km (0.72 astronomical unit)

The surface area is 460 million square kilometers.

Surface gravity 8.78m/s2

Autobiography time -243.02 days

Escape velocity10.4km/s

The lowest average surface temperature is the highest.

737K 750K 773K

Venus is the goddess of love and beauty, and also the goddess in charge of fertility and navigation, which is her name in Roman mythology; In Greek mythology, her name is Avelotti. Venus rises from the sea. It is said that at the beginning of the world, the goddess Kaya, who ruled the earth, combined with Uranus, who ruled heaven, and gave birth to a group of giants. Later, the husband and wife turned against each other. In a rage, Chaya ordered his youngest son, Cronus, to cut his father with a sickle. Uranus' flesh fell into the sea, producing bubbles, and Venus was born. In Greek, "Avelot Dede" means foam.

In the original plan proposed by the Planetary Definition Committee, besides determining Venus, Saturn, Jupiter, Mercury, Earth, Mars, Uranus and Neptune as classic planets, Pluto was also downgraded to a second-class planet, and ceres, Ka Rong and Zena numbered 2003UB3 13 were added as second-class planets.

Jupiter, called Jupiter in ancient times, is the fifth and largest planet from the sun, which is twice the mass of all other planets combined (3 18 times that of the earth). The period of Jupiter's revolution around the sun is 4332.589 days, which is about 1 1.86 years. Jupiter (also known as Jove) was called Zeus by the Greeks (king of gods, ruler of Mount Olympus, protector of Roman countries). This is Cronus (son of Saturn). )

Orbit: 778,330,000 kilometers (5.20 astronomical units) from the sun.

Planet diameter: 142984 km (equator)

Mass: 1.90 * 10 27kg

Jupiter is the fourth brightest object in the sky (second only to the sun, the moon and Venus; Sometimes Mars is brighter), Jupiter has been known to mankind as early as prehistoric times. According to Galileo's observation of Jupiter's four moons: Io, Europa, Ganymede and Callisto (now often called Galileo's moons) in 16 10, it was the first time that they were found not to orbit the earth, and it was also the main basis for agreeing with Copernicus's Heliocentrism about planetary motion.

The gaseous planet has no solid surface, and the density of gaseous matter only increases with the increase of depth (we calculate its radius and diameter from the point where its surface is equivalent to 1 atmosphere). What we usually see is the cloud top in the atmosphere, and the air pressure is slightly higher than 1 atmospheric pressure.

Jupiter is composed of 90% hydrogen, 10% helium (atomic number ratio, 75/25% mass ratio) and trace amounts of methane, water, ammonia water and "stones". This is very similar to the composition of the original solar nebula that forms the whole solar system. Saturn has similar composition, but Uranus and Neptune have less hydrogen and helium.

The information we obtained about Jupiter's internal structure (and other gaseous planets) came from indirect sources and remained stagnant for a long time. (Galileo's Jupiter atmospheric data only detected150km below the clouds. )

Jupiter may have a rock core, which is equivalent to the mass of 10- 15 earths.

In the inner core, most planetary materials are concentrated in the form of liquid hydrogen. These most common formal foundations on Jupiter may only exist under the pressure of 4 billion bar, which is the internal environment of Jupiter (and Saturn). Liquid metallic hydrogen consists of ionized protons and electrons (similar to the interior of the sun, but at a much lower temperature). Under the temperature and pressure inside Jupiter, hydrogen is liquid, not gaseous, which makes it the electron director and source of Jupiter's magnetic field. This layer may also contain some helium and some ice.

The outermost layer is mainly composed of ordinary hydrogen and helium molecules, with liquid inside and vaporized outside. What we can see is the higher part of this deep layer. Water, carbon dioxide, methane and other simple gas molecules are also rare here.

The mixture of ammonia ice, ammonium hydrosulfide and ice water is thought to exist in three distinct clouds. However, the preliminary results proved by Galileo show that these substances are extremely rare in the cloud (one instrument seems to have detected the outermost layer, and the other may have detected the second outer layer at the same time). However, the location of the surface proved this time is very unusual-Earth-based telescope observation and closer observation by Galileo spacecraft show that the selected area may be the warmest and partly cloudy area on Jupiter's surface at that time.

The atmospheric data from Galileo also proved that there was much less water there than expected. At first, it was estimated that the oxygen content in Jupiter's atmosphere was twice that of the current sun (including enough hydrogen to generate water), but at present its concentration is actually lower than that of the sun. Another surprising news is the high temperature and density of the outer atmosphere.

There are high-speed hurricanes on the surface of Jupiter and other gaseous planets, which are confined to a narrow latitude range, and the winds near the latitude blow in the opposite direction. Slight chemical composition and temperature changes in these zones create colorful ground zones, which dominate the appearance of the planet. Bright surface areas are called bands, and dark areas are called bands. These zones on Jupiter have been known for a long time, but these bounded eddies were first discovered by the Voyager spacecraft. The data sent back by Galileo spacecraft showed that the surface wind speed was much faster than expected (over 400 mph), and extended to the observable roots, extending several Qian Qian meters inward. Jupiter's atmosphere has also been found to be quite disordered, which shows that hurricanes mostly move quickly because of the heat inside them, rather than only getting heat from the sun like the earth.

The colorful clouds on Jupiter's surface may be caused by subtle differences in chemical composition and its role in the atmosphere, and may be mixed with a mixture of sulfur, resulting in colorful visual effects, but the details are still unknown.

The color change is related to the height of the cloud: the lowest point is blue, followed by brown and white, and the highest point is red. We can only see the clouds below through the holes in the clouds above.

As early as 300 years ago, Earth observation discovered the Great Red Spot on Jupiter's surface (this discovery is usually attributed to Cassini, or robert hooke in17th century). The Great Red Spot is an ellipse with a length of 25,000 kilometers and a span of12,000 kilometers, which can accommodate two earths. Other smaller spots have been around for decades. The observation of infrared ray and the inference of its rotation trend show that the Great Red Spot is a high pressure area, where the cloud top is particularly high and colder than its surroundings. A similar situation exists on Saturn and Neptune. It is not clear why this structure can last so long.

Jupiter radiates more energy than it receives from the sun. Jupiter is very hot inside: the core temperature may be as high as 20,000 Kelvin. This heat output is produced by Kelvin-Helmholtz principle (slow gravity compression of planets). Jupiter doesn't produce energy through nuclear reactions like the sun. It is too small and the internal temperature is not enough to cause a nuclear reaction. These internal heat may greatly trigger the convection of Jupiter's liquid layer and cause the complex movement of the cloud top as we see it. Saturn and Neptune are similar to Jupiter in this respect, but strangely, Uranus is not.

Jupiter conforms to the maximum diameter that a gaseous planet can reach. If the composition increases again, it will be compressed by gravity, so that the global radius will only increase a little. A star can only get bigger because of its internal heat source (nuclear energy), but Jupiter must be at least 80 times bigger to become a star.

The survey results sent back by the spacecraft show that Jupiter has a strong magnetic field, and its surface magnetic field intensity is 3 ~ 14 gauss, which is much stronger than the earth's surface magnetic field (the earth's surface magnetic field intensity is only 0.3 ~ 0.8 gauss). Jupiter's magnetic field, like the earth's, is dipole, and there is an inclination of 10 8' between the magnetic axis and the rotation axis. Jupiter's positive magnetic pole is not the North Pole, but the guiding pole, which is just the opposite of the situation on the earth. Due to the interaction between Jupiter's magnetic field and the solar wind, Jupiter's magnetosphere is formed. Jupiter's magnetosphere is large in scope and complex in structure. The huge space between 0/0.4 thousand and 7 million kilometers from Jupiter/KLOC-is Jupiter's magnetosphere. The magnetosphere of the earth is only within 7 ~ 8 kilometers from the center of the earth. Jupiter's four large moons are shielded from the solar wind by Jupiter's magnetosphere. There is a radiation belt around the earth, called the Van Allen Belt, and there is such a radiation belt around Jupiter. Voyager 1 also found that Jupiter has 30,000 kilometers of Northern Lights on its side facing away from the sun. 198 1 At the beginning of the year, Voyager 2 was once again affected by Jupiter's magnetic field after it had already left Jupiter's magnetosphere and flew to Saturn. From this perspective, Jupiter's magnetic tail is at least 60 million kilometers long and has reached Saturn's orbit.

There are aurora at Jupiter's poles, which seems to be formed by the material ejected from the volcano on Io entering Jupiter's atmosphere along Jupiter's gravitational line. Jupiter has a halo. Halo system is the same feature of giant planets in the solar system, which is mainly composed of small stones and snow masses. Jupiter's rings are hard to observe. It is not as spectacular as Saturn, but it can also be divided into four circles. Jupiter's ring is about 6500 km wide, but its thickness is less than 10 km.

Jupiter's halo

Jupiter's rings are darker than Saturn's (albedo is 0.05). They are made up of many granular rock materials.

Jupiter has a ring similar to Saturn's, but it is small and weak. (Yes) Their discovery was purely unexpected, just because the scientists of the two travelers 1 insisted on sailing 1 100 million kilometers. We should see if there is a halo. Others think that the possibility of finding a halo is zero, but it actually exists. What a clever plan these two scientists have come up with. Later they were photographed by telescopes on the ground.

Particles in Jupiter's rings may not exist stably (influenced by the atmosphere and magnetic field). In this way, if the ring is to keep its shape, it needs to be constantly supplemented. Two small satellites operating in the halo, Io XVI and Io XVII, are obviously the best candidates for halo resources.

The exploration of Jupiter's atmosphere by Galileo spacecraft found that there is a strong radiation belt between Jupiter's aura and the outermost atmosphere, which is about ten times that of the ionosphere. Surprisingly, the newly discovered band contains high-energy helium ions from unknown sources.

1In July, 994, comet Shoemaker-Levi 9 collided with Jupiter, which was an amazing phenomenon. Even amateur telescopes can clearly observe surface phenomena. Nearly a year later, Hubble telescope can observe the debris produced by the collision.

Jupiter is the brightest star in the sky (second only to Venus, but Venus is often invisible in the night sky). Four Galileo satellites can be easily observed with binoculars; The band of light and the great red spot on Jupiter's surface can be observed through a small astronomical telescope. Mike. Harvey's planet search map shows the positions of Mars and other planets in the sky. More and more details and better charts will be discovered and completed by astronomical programs such as Brilliant Galaxy.

In the past, people speculated that there was a dust layer or dust ring near Jupiter, but it has not been confirmed. 1 In March, 979, the navigator1photographed Jupiter's halo. Soon, "Voyager 2" got more information about Jupiter's halo, and finally confirmed that Jupiter also has a halo. Jupiter's halo is shaped like a thin disk, with a thickness of about 30 kilometers and a width of about 6,500 kilometers, which is about 0/.28 million kilometers away from Jupiter/kloc-0. The halo is divided into an inner ring and an outer ring. The outer ring is bright and the inner ring is dark, almost touching Jupiter's atmosphere. The spectral type of the halo is G type, and the halo also surrounds it? /ca & gt；

Looking at Polaris, this star does Sunday exercise counterclockwise.

All constellations have the phenomenon of rising in the east and setting in the west, but Polaris is very close to the north celestial pole, so only the apparent motion of Polaris is almost invisible.

Astronomy is the basic subject of natural science. It is a subject that mainly observes and explains the material conditions and events of celestial bodies. It mainly studies the distribution, movement, position, state, structure, composition, nature, origin and evolution of celestial bodies. In ancient times, astronomy was also closely related to the formulation of calendars. The difference between astronomy and other natural sciences is that the experimental method of astronomy is observation, through which all kinds of information of celestial bodies are collected. Therefore, the study of observation methods and means is a direction that astronomers strive to study. Physics and mathematics have a great influence on astronomy, and they are indispensable theoretical AIDS for modern astronomical research.

The average distance between the moon and the earth is about 384,400 kilometers.

The average distance from the sun to the earth is 149597900 km.

So it becomes a star because its mass is large enough and its internal pressure is large enough to cause the fusion of matter to emit light and heat, and if its mass is large enough, its gravity will dominate the center of the galaxy, right? But is there such a situation? Is a galaxy full of glowing hot stars or cold dark stars? Of course, there is no galaxy without a rotating core, so there are no planetary stars at all?

If the star as the center dies, the surrounding stars will either be swallowed up in their last white dwarf or supernova state, or the weakened gravity will disappear into the vast universe.

Galaxies are unlikely to be all stars. In the end, there will be a space of gravity balance between stars, and there will be some rocks or dust in this space.