Astronomers of the past, watching the black “hole” of Venus, was moving against the background of the solar disk, were able to calculate the distance from Earth to the sun, get the first data about the atmosphere of Venus. Modern scholars through this event will be able to refine search techniques of planets around other stars and the signs of life on them.
Transit of Venus will be seen everywhere except in South America, Antarctica and West Africa. However, all phases of the passage (or transit, as astronomers say) will be visible only in eastern Australia and eastern China, the Russian Far East, Siberia, on the northern Urals and the northern coast of the Kola Peninsula. In other regions of the sun, or go down before the end event, or rise with Venus already on the disk.
What is this?
Venus once every 584 days crosses the line Sun-Earth system. If the plane of the orbits of Venus and the Earth’s match, almost every two years, was observed to transit – Venus would be passed directly between Earth and the Sun, and we would see her silhouette against the background of the solar disk.
But the Venusian orbit is inclined to the earth by 3.39 degrees, so that such events occur much less frequently.
Full cycle covers 243 years, it includes two pairs of passages, separated by an interval of eight years. The first passage in the pair is observed in December, the second – in June. From the first pair of passes to the second cycle of 121.5 years, between the second and the end of the cycle – 105.5 years. Then the cycle repeats.
The last time the passage was observed in 2004, and the next pair of transits will occur in 2117 and 2125 years.
There is some evidence that the ancient Babylonians in the 16th century BC saw some astronomical events associated with Venus and the Sun. However, the texts on clay tablets, can not serve as clear evidence that this was just the passage of Venus across the solar disk.
For the first time the possibility of such an astronomical event predicted the discoverer of the main laws of celestial mechanics, Johannes Kepler. Using data collected by the Danish astronomer Tycho Brahe, Kepler predicted a transit of Venus Dec. 6, 1631. Unfortunately, this event if you can not be seen in Europe.
The first documented observation of the transit of Venus refers to the December 4, 1639: British priest Jeremiah Horrocks and his friend William Crabtree were able to first determine the angular diameter of Venus, as well as the most accurately calculated the distance from Earth to the Sun, having received the value of 96 million kilometers (according to modern data 149, 6 million kilometers).
By the time of transit of 1761 was organized by one of the world’s first astronomical campaigns: more than 100 people have observed this phenomenon in different parts of the globe in order to determine the distance to the sun. That’s when Mikhail Lomonosov first noticed the appearance of a glowing rim around the sun, and interpreted this as an indication of the presence of the atmosphere.
The next time, in 1769, also participated in the observations of many scientists. In particular, on the island of Tahiti on the ship “Endeavour”, under the command of James Cook’s expedition traveled the whole of British scientists, and in Russia in the event of observing even the Empress Catherine II.
On Earth and in space
The current transit of Venus across the solar disk will be watching a lot of amateur astronomers and professionals, using space and ground instruments.
In particular, the observations will attend the famous orbiting telescope “Hubble”. Look directly at the sun he can not – the sunlight hurt his light-sensitive matrix. Therefore, the “Hubble” will look into the “mirror” – to the moon. Astronomers using the Space Telescope will try to isolate the microscopic changes in the brightness of the moon, related to the fact that some of the sun’s surface close Venus. “Hubble” will have to “catch” the fraction of solar radiation which has passed through the atmosphere of Venus, and to explore with the spectroscopy of its chemical composition.
Since the composition of the Venusian atmosphere is well known, this experiment will determine whether the same method to study the atmospheres of planets around other stars, and how small gas components so you can detect.
The European probe “Venus Express” will be paired with a team of European scientists on Svalbard: they will both watch the passage of Venus across the solar disk, which will help to work out methods for finding traces of life in the atmosphere of exoplanets.
A team of astronomers in the experiment, “Twilight of Venus” (Venus Twilight Experiment) planned by simultaneous observations from different regions of the world to study carefully the composition of the Venusian atmosphere, as well as detailed vyyasnt as Mikhail Lomonosov was opened by the atmosphere of this planet.
From space for the transit of Venus will be watching the crew of the International Space Station. American astronaut Don Pettit plans to monitor the passage of Venus from the module “Dome” – a giant viewing window on the ISS. Especially for this module will be removed from the windows inside the protective glass to protect them from scratches.
Astronomers in particular, expect to see the so-called “Ring of Fire” – a bright ring around the disk of Venus, which appears when the planet is on the background of the sun. The appearance of a ring of fire due to the refraction – refraction of light in the upper atmosphere of Venus above the clouds.
In observing the transit of Venus will also be involved Probe NASA SDO and the Japanese Hinode.