Telescopic Observations The first explorations of the solar system were initiated by telescopes, when astronomers first began to map objects that were too dim to be seen by the naked eye.

Galileo Galilei was the first astronomer to discover the details of celestial bodies in the solar system.

He discovered craters on the moon, sunspots on the surface of the sun, and four satellites surrounding Jupiter.

Huygens followed Galileo's discoveries and discovered the shape of Saturn's moon Titan and its rings.

Subsequent Cassini discovered four satellites of Saturn, as well as the Cassini Slit of Saturn's rings and the Great Red Spot of Jupiter.

In 1705, Edmond Halley realized that the comet that appeared in 1682 was actually a comet that reappeared every 75-76 years, now called Halley's Comet.

This was the first evidence that objects other than planets orbited the sun.

In 1781, William Herschel discovered a binary star in the constellation Taurus while observing what he thought was a new comet.

In fact, its orbit revealed a planet, Uranus, the first planet to be discovered.

In 1801, Giuseppe Piazzi discovered Ceres, a small world between the orbits of Mars and Jupiter, which was initially thought to be a planet.

However, subsequent discoveries increased the number of small objects in this region to tens of thousands, leading to their reclassification as asteroids.

By 1846, errors in Uranus's orbit led many to wonder whether another large planet was exerting a force on it from afar.

Eban Le Verrier's calculations eventually led to the discovery of Neptune.

In 1859, because there were some small movements at the perihelion of Mercury's orbit that could not be explained by Newtonian mechanics ("Mercury's perihelion precession"), some people hypothesized that there was an inner water planet, Zhu Rongxing (often translated as "Vulcan" in Chinese); however,

This motion was eventually proven to be explained by general relativity, but some astronomers have not given up on the search for "water planets."

In order to explain the obvious deviation in the orbits of the outer planets, Percival Lowell believed that there must be a planet outside it, and called it Planet X.

After his death, its Lowell Observatory continued the search, and Pluto was finally discovered by Tombaugh in 1930.

However, Pluto is too small to affect the orbit of the planet, so its discovery was purely coincidental.

Like Ceres, it was initially considered a planet, but many objects of similar size were discovered in nearby areas, so Pluto was reclassified as a dwarf planet by the International Astronomical Union in 2006.

In 1992, astronomers David Jewett of the University of Hawaii and Jenny Lu of MIT discovered 1992 QB1, which turned out to be a new population of icy, asteroid-like belts now known as the Kuiper Belt.

, Pluto and Charon are both members.

Eris, announced in 2005 by Michael Brown, Chad Trujillo, and David Rabinowitz, is a discrete disk object larger than Pluto and the largest object orbiting the Sun after Neptune.

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Spacecraft Observations Since entering the space age, many detections have been unmanned spacecraft detection missions organized and executed by space agencies in various countries.

All planets in the solar system have been visited by spacecraft launched from the Earth, and various studies have been conducted to varying degrees.

Although they were all unmanned missions, humans were able to view close-up photos of all planetary surfaces, and with the presence of landing craft, some experiments on the soil and atmosphere were also conducted.

The first man-made object to enter space was Sputnik 1 launched by the former Soviet Union in 1957, which successfully orbited the Earth for a year.

Pioneer 6, launched by the United States in 1959, was the first artificial satellite to send back images from space.

The first successful flyby of another celestial body in the solar system was Luna 1, which flew by the moon in 1959.

It was originally intended to hit the moon, but missed its target and became the first man-made object to orbit the sun.

Mariner 2 was the first human-made object to orbit another planet, orbiting Venus in 1962.

The first successful orbit of Mars was Mariner 4 in 1964.

It wasn't until 1974 that Mariner 10 went to Mercury.

The first spacecraft to detect an exoplanet was Pioneer 10, which flew by Jupiter in 1973.

In 1979, Pioneer 11 became the first spacecraft to visit Saturn.

The Voyager program launched two spacecrafts in 1977 to conduct large cruises of the outer planets, visited Jupiter in 1979, and visited Saturn in 1980 and 1981.

Voyager 2 continued its approach to Uranus in 1986 and Neptune in 1989.

The Voyager spacecraft has moved far beyond the orbit of Neptune and continues on its path to discover and study terminal shocks, the heliosphere and the heliopause.

According to NASA, the two Voyager spacecraft have been exposed to terminal shock waves at about 93 astronomical units from the sun.

No spacecraft has ever visited a Kuiper Belt object.

New Horizons, launched on January 19, 2006, will become the first man-made spacecraft to explore this area.

The unmanned spacecraft is expected to fly by Pluto in 2015.

If this proves feasible, the mission will be expanded to continue observing some other Kuiper Belt objects.