Science Talk

Author: Yu Xiangzhong / Country: Mainland China
Publisher:
Publish Date: 2006-07-01
Features: The content of this book has been authorized for use by SBS Radio Australia. Scientists who have traveled to Australia passionately explain the latest global science information to a broad readership. The content is rich, the information is up-to-date, and the language is humorous, serving as an introduction to the study of science and guiding people to explore the scientific truth behind the ordinary phenomena of the vast world. The book was originally a speech manuscript by the author for the Chinese program on SBS Radio Australia. After being organized, it was compiled into short essays. It is the author's introduction to the relatively novel developments in science and technology in Western countries to Chinese friends in Australia. SBS Radio (Special Broadcasting Service Corporation) is a multicultural radio owned by the Australian government. Its daily Mandarin Chinese broadcast program has been a great help to the Chinese living in Australia. From 1994 to 2000, the "Science Talk" program was broadcast weekly on SBS Radio for 10 minutes each time, introducing the latest global science information and complex scientific issues to Chinese intellectuals in Australia in an easy-to-understand way, thus receiving widespread praise and recognition from the audience. The phenomenon of a solar eclipse provides a valuable opportunity for space science research.
The two astronomical phenomena of solar and lunar eclipses have always attracted people's attention since ancient times. All recorded solar and lunar eclipses throughout history provide modern astronomers with strong evidence to prove their theories. The occurrence of a solar eclipse is because the moon moves between the sun and the Earth's orbit, casting its shadow on the Earth and blocking the direct sunlight, so that people under the moon's shadow cannot see the sun for a while, only the black shadow of the moon, which is a solar eclipse. On the other hand, the occurrence of a lunar eclipse is exactly the opposite of a solar eclipse, where the Earth moves between the sun and the moon, blocking the sunlight and causing the moon to appear dark. These two astronomical phenomena occur several times a year, being phenomena that have existed since the formation of the Earth and moon. Whenever a solar or lunar eclipse occurs, strange reactions appear among the creatures on Earth. For example, bats, which are only active at night, will fly out during a total solar eclipse. Other animals also exhibit abnormal behavior, as if the weather were changing. According to historical records, when Alexander the Great was campaigning eastward, a lunar eclipse occurred just before the battle against King Darius of ancient Persia. The soldiers of both armies were in a panic, especially the Greek soldiers, who were far outnumbered by the million-strong Persian army. However, Alexander had an idea and ordered his troops to say that the sun of Macedon had blocked the moon of Persia. Upon hearing this explanation, the soldiers immediately stabilized their morale and boosted their fighting spirit. On the other hand, the Persian soldiers were frightened by this sudden celestial phenomenon, and their morale suffered. When the two armies faced each other, the Persians were defeated and fled. This is one of the most famous stories of how an astronomical phenomenon influenced history.
Scientists have made very precise calculations of the orbits of the Earth, moon, and sun. Years before each solar or lunar eclipse occurs, accurate predictions can be made. The regions from which a solar eclipse can be seen on Earth can be calculated long in advance, allowing people to make preparations in advance. As a result, some tour groups are organized to observe solar eclipses, and the business is very good. For example, on February 26, 1998, when a total solar eclipse occurred in South America, several cruise ships carried thousands of tourists specifically to witness the eclipse.
Astronomers calculate that during a solar eclipse, the moon casts a shadow about 240 kilometers wide on Earth, moving at a speed of 2,400 kilometers per hour. People within this shadow can see a total solar eclipse, while those near the shadow can see a partial solar eclipse. Because this shadow moves so quickly, it stays in one place for less than 5 minutes, and only during these 5 minutes can a total solar eclipse be seen. At this time, people see the sun as a black ring in the center, called the "diamond ring," which is the most attractive part of the eclipse. However, whether one has the luck to see such a celestial wonder depends on the local weather—only under clear, cloudless skies can such an astronomical spectacle be enjoyed.
The phenomenon of a solar eclipse not only creates opportunities for the tourism industry but also presents a research opportunity for scientists. This is because, during a solar eclipse, not only do many animals exhibit abnormal behavior, but many physical phenomena are also affected, such as radio broadcasts. Current research on solar science has discovered that the sun emits a halo of light, which has a very high temperature, exceeding 1 million degrees Celsius, while the surface temperature of the sun is only about 6,000 degrees Celsius. To study this phenomenon, the best time is during a total solar eclipse, because the strong direct sunlight of the sun is blocked by the moon, but the halo is still visible. Therefore, within the 5 minutes of a total solar eclipse, it is the best time to observe the halo. During each total solar eclipse, many astronomers bring tons of equipment to places with the best weather, where the eclipse will not be obscured by clouds, to use the rare 5 minutes to measure the temperature and movement of the halo.
NASA has specially equipped a Boeing 747 plane with various observation instruments, allowing it to chase the moon's shadow at an altitude of 10,000 meters, thus extending the observation time to 15 minutes. This shows how rare the opportunity is. Everything between the sun and the Earth is interconnected. It is not only the ultimate source of energy for Earth's organisms but also any phenomenon that occurs on the sun will affect the Earth. For example, when sunspot clusters reach their activity peak every 11 years, communications on Earth are greatly affected.
Moreover, the ongoing nuclear fusion of hydrogen in the sun's core is the source of its heat. However, these hydrogen fusion reactions occasionally produce very powerful explosions. The flames from these explosions shoot out tens of millions of kilometers into space, and the radiation they produce strikes the Earth's magnetic field at the outer edge, causing intense auroras. In severe cases, the interaction between radiation and the magnetic field can generate a large amount of static electricity. Excessive static electricity in the atmosphere can cause malfunctions in electronic transmission systems on the ground. In the past, Canada experienced a nationwide power outage, which was caused by the impact of a solar storm.
People in space, such as those on satellites and space stations, may also be harmed by the radiation from solar storms. Therefore, studying the causes of solar storms and establishing early observation methods require using data obtained from the study of total solar eclipses to make evaluations.
There is now a satellite in space specifically designed to observe all phenomena of the sun, which creates artificial total solar eclipses on the satellite. However, this artificial total solar eclipse covers a very small area and cannot be compared to a natural one. As a result, scientists still travel to regions where total solar eclipses occur to seize the precious 5 minutes for observation, collecting data to design better solar observation satellites.
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