What is an astronomical clock?

Astronomers have found that if a fast-rotating pulsar in Marina is used as a timer, its error will be every 3 million years 1 second, which is 10 times more accurate than the current "atomic clock". Therefore, astronomers call it "astronomical clock".

Pulsar is one of the four major discoveries in astronomy in 1960s. It has a fairly stable and short pulse period. Generally speaking, it is a fast-rotating neutron star or a fast-rising and shrinking neutron star. The density of matter in pulsars is very high. A matchbox-sized substance actually weighs 2 billion tons. Because it has such a high material density and the strong interaction between internal electric field and magnetic field, it can rotate quickly without disintegration.

Pulsar is a very strange star, it constantly sends out radio pulses regularly, and always sends out radio signals regularly, just like pulse beating. The pulse period of different pulsars is long and short, the long one is a few seconds, and the short one is only a few tenths of a second, but the pulse period is very accurate.

Why do radio waves emitted by pulsars have precise periods? It is generally believed that neutron starlight has a structure called "lighthouse" (some areas where radiation is concentrated), which constantly emits strong radio waves. Every time the neutron star rotates, the "lighthouse" points at us once, and people receive radio waves once.

Who discovered pulsars? 1967 In August, Ish, a professor at Cambridge University, and Bell, a graduate student, accidentally recorded a pulse image while observing the radio source of a huge antenna array with an area of over 20,000 square meters. This is puzzling, and the observer said humorously, "This is a signal from a short green man." After a period of repeated observation, it is determined that this is a special new celestial body-pulsar.

This pulsar is called CP 19 19(CP is the abbreviation of pulsar discovered by Cambridge University,19 is the coordinate number of this star), and its pulse period is 7.33730 1344 seconds, accurate to 9 decimal places! In other words, its accuracy is as high as one hundredth of a second! 20 times higher than cesium atomic clock.

Later, the United States, Australia and other countries have observed many pulsars, which have reached more than 330 so far.

Although pulsars are called stars, in fact, even the largest optical telescopes can't see them, and usually only radio telescopes can receive their pulse signals.

Generally, pulsars are only found to have radio pulses, and some pulsars are also found to have light pulses. The observation records of China ancient 1054 supernova explosion provide very valuable information for the formation and evolution of pulsars.

One morning in July 1054, astronomers in Qin saw an amazing astronomical phenomenon. A celestial body brighter than Venus has appeared in the east for 23 consecutive days and can be seen during the day. Then the brightness gradually weakened, and it was completely out of sight after more than 60 days. The History of Song Dynasty recorded all the stories of this guest star, calling it "1054". After its eruption, it left a cloud-like relic, which was photographed with a telescope and shaped like a crab, so it was called the Crab Nebula. It is still sending radio waves everywhere.

Scientists believe that the astronomical clock is the most accurate clock in the universe. In the future space exploration, pulsars can replace the atomic clock as a timer for interstellar flight.