Combining strict thinking with known imagination is useful, and the imagination pushes the researcher to new discoveries. Thus, Olbers expressed the bold idea that the place of the solar system, which some people gave only to the planet, was once occupied by a single planet. Two of them, discovered here — according to Olbers, — are the fragments of it, formed by some once catastrophic event. These fragments, perhaps, are not even two, but many, and it makes sense to look for the rest.
If once a planet that was placed between Mars and Jupiter was torn to pieces, the orbits of all the received fragments should pass through the point of space where the explosion occurred. This is a well-known law of mechanics, which should be fair here. If so, then what to fumble through a large area of the sky in search of new planets, it is easier to wait for them when they will pass through those points where the orbits of Ceres and Pallas crossed. Here was a practical conclusion from the assumption described above, which can be called a “working hypothesis”.
The “working hypothesis” is an assumption that is sought to be made temporarily to explain a newly discovered fact, at least the fact itself has not yet been studied in such detail that the hypothesis is well-founded. The working hypothesis, without pretending to be strict, provides some initial explanation of the facts and guides the researchers in their search. Further studies are then developed not blindly, but in a certain direction, and above all to verify the correctness of the hypothesis made. After all, some conclusions follow from the hypothesis, for example, that there should still be such and such phenomena. Whether they really exist or not, that's what the attention is immediately switched to. If the hypothesis is not justified, it is replaced by a new and already more perfect one, because the first one has led us to a deeper understanding of the open facts and added new data.
Three years Olbers himself patiently waited for new planets in the constellation of the Virgin, where the point of intersection of the orbits of Ceres and Pallas was visible from the Earth. His work was rewarded in 1807 with the discovery of Vesta. But in 1804 Garding opened the planet named Juno in the constellation of China, where there was a second point of intersection of orbits. Thus, it seemed that the hypothesis was confirmed, and the orbits of the four fragments found crossed almost at the same points. However, if to think about it, Olbers' hypothesis would be valid only in case of the recent catastrophe with the missing big planet.
In fact, if this event occurred long ago, the attraction from the big planets had to change the orbits of fragments so strongly and variously that they could not continue to intersect at the same points.
The planets discovered afterward (still there, between Jupiter and Mars) do not pass through the places where the orbits of the first four open planets crossed. The initial impression of the correctness of Olbers' assumption was based on a random coincidence... All this turned out, however, much later than Olbers found the fourth planet.
When everyone involved in the discovery of these planets died, the fifth planet was still not caught by the observers. It was not until 1845, almost 40 years later, that it was discovered. It was opened by retired postal official Genke, whose patience is truly amazing. 15 long years, from evening to evening, he was looking for fellow travelers Ceres and her companions, and every new evening, bringing disappointment did not weaken his enthusiasm. Two years after his first success, he discovered another planet, and soon afterward the discovery of such planets began uninterruptedly.
All the planets found between the orbits of Mars and Jupiter received the common name of small planets or asteroids, which translates from Greek means “starlike. Indeed, even in the strongest telescopes, these planets look like stars, so they are small. Little in astronomy — a concept, of course, relative, but compared to the rest of the planets asteroids are tiny. The biggest — Ceresera has about 1000 km across and by volume is so many times less than the Moon, how many times smaller than the Earth.
Pallada has a diameter of about 600 km, Juno has about 250 km and Vesta has about 540 km. Only they, and with the help of the world's greatest refractors, can see a tiny disk. Their diameters can be measured, but no details can be seen on them. The other asteroids are much smaller in cross-section, and they are evaluated by the luster of these bodies. With the same surface reflectivity and the same distance from the Earth and the Sun, the visible luster of the planet is proportional to the square of its diameter.
To be continued in the next part https://zen.yandex.ru/media/id/5d92f1673d873600b11d9f29/nature-does-not-tolerate-emptiness-a-little-bit-about-asteroids-part-4-5d9442d198930900af86fa8a