The most noteworthy astronomical phenomenon in the near future is Mars opposition to the sun , which is also a good time to appreciate Mars !
Mars opposition
The most noteworthy celestial phenomenon in the near future is Mars opposition celestial, which only happens every two years and two months on average. When Mars opposes the sun, the earth runs between Mars and the Sun. Mars and the Sun are located on both sides of the Earth, with a difference of 180 degrees in the sky. When the sun sets, Mars rises from the east. By midnight, Mars is located directly south with the highest horizon, and by the morning when the sun rises from the east, Mars sets in the west. Therefore, Mars can be seen all night. When Mars opposes the sun, Mars is closer to Earth, it has the brightest brightness and looks larger in the telescope, which is the best time period for observation of Mars.
Schematic diagram of Mars position on the evening of December 8th Picture source: star map software
The time of Mars opposition to the sun was December 8th. During the opposition period, Mars is in Taurus, with the brightest brightness up to -1.9, etc. As the sky darkened, red Mars rose from the northeastern horizon.
Schematic diagram of Mars' position on the evening of December 1st Image source: Star map software
December 1st, Mars was closest to the earth during this opposition period, and the closest distance to the earth was about 81.4 million kilometers. By the time of opposition on December 8, the distance between Mars and Earth increased to 82.2 million kilometers, about 800,000 kilometers more than the nearest time.
Why isn't it the day when Mars opposition is
closest to the earth?
This is because neither the orbits of Mars nor the Earth are perfect circles but ellipses of a certain degree, so when the two are closest, they often occur within a few days before or after the collision day.
Sun Echo is a phenomenon that only planets orbiting outside of the Earth orbit. Mars is our closest neighbor. It counts out of the Earth's orbit, from the sun, and it is the fourth big planet . Mars looks like a striking fiery red star. Since Mars and Earth are both rotating around the sun in their respective orbits, the distance between them is always changing, which makes the brightness of Mars we see constantly changing. When far away from Earth, Mars' brightness is darker, and the brightness at its darkest is only 1.5. When it is closest to the earth, its brightness is very bright, and its brightest can reach -2.9 or above, exceeding the brightness of Jupiter , second only to Venus, becoming the second brightest star in the sky.
The big opposition of Mars
The opposition of Mars has a significant feature. Every time it opposes the sun, the distance between it and the earth is quite different, resulting in the brightness and size of Mars we see. It is rare to encounter a close-range opposition between Mars and Earth, so there is also the saying that Mars is a major opposition. What's going on?
This is due to the different characteristics of Mars and Earth's orbits. Planetary orbits are all elliptical, but the degree of elliptics is different. Mars' orbit is relatively more elliptical, while the Earth is closer to circular. Mars is closest to the sun, that is, when it crosses the perihelion, it is about 207 million kilometers away from the sun. At the arising point, the distance is more than 249 million kilometers, a difference of more than 42 million kilometers. When Mars encounters opposition to the Sun near the perihelion point, the distance to the Earth is relatively close, and the closest can reach about 56 million kilometers. When it encounters opposition to the Sun near the apogee, the distance is relatively far from the Earth, and the farthest can be more than 100 million kilometers. The distance between the two is more than 40 million kilometers. The closer the celestial bodies are to us, the larger they will look and the clearer they can see. It is also an opposition to the Sun. Generally speaking, people will definitely choose to observe Mars at close range.
The day when Mars opposes near the perihelion is called the Mars major opposition, and it only occurs every 15 to 17 years. At this time, because it is very close to the earth, the brightness of Mars is very bright, and it looks relatively large in the telescope. Astronomically, the size of a planet's appearance is called the apparent diameter, which is expressed in angle seconds. During the period when is rushing to , the apparent diameter of Mars can reach 24 arc seconds, and at extremes it can even exceed 25 arc seconds. This number is actually not large if compared with Jupiter. Jupiter's apparent diameter is generally around 40 arc seconds, and it can be close to 50 arc seconds during the opposition period.But for Mars, this is already the limit it can reach, and it only lasts for a short period of time before and after the big rush, and the opportunity is very rare.
The last major opposition to Mars occurred on July 27, 2018. At that time, Mars was only 57 million kilometers away from the Earth, with a maximum brightness of -2.8, and a maximum apparent diameter of 24.3 arc seconds. This year, the distance between Mars and us has increased to about 82 million kilometers, with the maximum brightness of -1.9, and the maximum diameter of the diameter can only reach more than 17 arc seconds. It is a medium to lower level.
The next two oppositions to the sun, the distance between Mars and Earth is longer and farther than that. The next time Mars opposition to the Sun will be until January 16, 2025, when Mars' maximum brightness is only -1.4, and the maximum apparent diameter is less than 15 arc seconds. The observation effect is not as good as this year's opposition to the Sun. On February 19, 2027, the opposition to the sun reached its peak. The distance between Mars and us was more than 100 million kilometers, with a maximum brightness of only -1.2, which is darker than the brightest star, , Sirius , and its apparent diameter is only 13.8 arc seconds, which is almost half smaller than the time of Mars' large opposition. It is a veritable "small opposition" of Mars.
Source: Beijing Planetarium
Process Editor: TF022
