After the vernal equinox on Earth, let’s take a look at what the vernal equinox is like on other planets.

During the spring equinox, many places in my country are bright and sunny, with willows growing green... So for us who have entered the space age and are moving step by step towards deep space, is there a spring equinox on other planets in the solar system?

In fact, not only does the Earth have a vernal equinox, but some other planets in the solar system also have a vernal equinox, such as Mars and Saturn. So, what does the vernal equinox mean for these planets?

Mars: The Spring Equinox is the beginning of the New Year

According to the definition of the vernal equinox on Earth, all planets that revolve around the sun, have a spherical shape, and a stable rotation axis can have a vernal equinox.

For example, Mars, a close neighbor of the Earth, has an orbital period and axial inclination that are relatively close to those of the Earth. Not only does it have the vernal equinox, but this day is also a big day for it - if you happen to arrive on Mars on November 12, 2024 , then congratulations, you have just caught up with the 38th New Year of Mars!

For Mars, this day means that the sandstorm weather that has ravaged Mars for months is about to end because the vernal equinox has arrived.

In winter, when Mars is near perihelion, the southern hemisphere is heated by direct sunlight, while the northern hemisphere gradually enters an extremely cold period, with temperatures dropping to more than 100 degrees below zero. The huge temperature difference between the northern and southern hemispheres provides excellent conditions for atmospheric movement. Therefore, although the atmosphere on Mars is extremely thin, strong winds with speeds of up to 180 meters per second will still blow up fine dust on the ground, forming a red dusty sky that can be seen from Earth.

After the vernal equinox, as the sun's direct position gradually shifted towards the northern hemisphere, the temperature difference between the northern and southern hemispheres began to narrow. The energy originally provided to the Martian atmospheric circulation was greatly weakened, the wind speed dropped significantly, and the sand and dust fell back to the ground.

The Martian dust storm activity is the most significant change on Mars that can be observed from Earth. Since 1955, humans have chosen the spring equinox as the new year of the Martian calendar, and 37 Martian years have passed so far.

Saturn: Come do some research on the spring equinox

Saturn is a giant gas planet that experiences an equinox approximately every 14 to 15 years.

Unlike other planets, Saturn has the most mysterious, elegant, and recognizable ornament in the entire solar system: the Saturn ring. This strip, which is more than tens of thousands of kilometers wide and only more than ten meters thick, is mainly composed of ice and dust.

When the spring equinox arrives, the sun will shine vertically on Saturn's rings. With this opportunity, we can discover some "details" that are difficult to see normally. For example, from July 2008 to August 2009, the man-made spacecraft "Cassini" that explored Saturn flew around Saturn more than 60 times, and finally completed a series of important explorations and obtained considerable scientific results by taking advantage of the key time point of the spring equinox.

On July 26, 2009, when the spring equinox of Saturn was approaching, Cassini discovered a satellite with a diameter of only about 400 meters under the strong light of the sun's direct hit on Saturn's rings . With such a "mini" body, it would be difficult to be discovered even if it was placed around the moon!

The discovery and detection of this satellite was due to the conditions created by the spring equinox of Saturn. When it cast a 41-kilometer shadow on Saturn's rings, its whereabouts were clearly exposed to the probe. After calculation and analysis, this "mini" satellite is 480 kilometers away from the outer side of the B ring, almost floating about 200 meters above the plane of Saturn's rings, and on normal days it almost blends in with the background rings.

Earth: Spring Equinox brings birdsong and flowers

Venus, Jupiter, and Mercury are like "hermits" with almost no seasonal changes. Uranus, as the planet with the coldest atmosphere in the solar system, is freezing cold all year round, making it impossible for people to feel the slightest hint of spring.

After a tour of the solar system, it is not difficult to find that the Earth, the "darling of heaven", is the most favored of all. Compared with other celestial bodies in the solar system, the perfect distance between the Earth and the Sun makes the Earth full of vitality.

On the earth, the spring equinox is full of birdsong and flowers, warm sunshine, gentle spring breeze, and gentle spring rain... It is very touching. In the "dark forest" of the universe, this "blue planet" is walking alone, but it provides humans with a home for all things to grow.

Source: Popular Science Times

Author: Han Dayang, Engineer, Space Weather Technology R&D Office, National Satellite Meteorological Center