Astronomical knowledge

Excerpted from Astronomy Enthusiast magazine.

Besides the sun and the moon, Venus is usually the brightest celestial body. As the brightest star in the night sky, it is bound to attract everyone's attention. During the period from September to the end of the year, if anyone talks about UFOs or abnormal bright spots in the western sky in the evening, it may be Venus. Venus can reach -4.9 when it is at its brightest, and it can also reflect shadows on moonless nights without light pollution.

Venus's orbit is inside the earth's orbit. On the celestial sphere, Venus can be as far away from the sun as 47 degrees. Venus can be seen when it is in the west of the sun in the morning. At this time, it is called the morning star. When Venus is in the east of the sun, you can see it at night. At this time, Venus is called the evening star. When the inner planet is farthest from the sun, it is called great distance. 1On October 30th, 202 1, 10, Venus will reach the easterly position. Because the angle between the ecliptic and the horizon will change, a large distance does not mean that the horizon is the highest. For observers near 40 degrees north latitude, Venus will reach the highest horizon in the near future at sunset on February 4+65438, which is also the brightest.

In fact, since August, the brightness of Venus has been considerable. For most parts of China, the reason why Venus began to enter the observation season in September is because Venus was already bright before September, but it still shines in the brilliance of the sun; After the civil blackout in September, the height of Venus can still reach the horizon that is easy to observe.

First of all, we need to emphasize the safety of observation. Although Venus can be seen before sunset, it is never safe to look directly at the sun. Try to observe Venus after sunset. Secondly, because Venus is very bright, it is not difficult to find it in the night sky as long as there are no clouds or other obstructions in the west. You can use the mobile phone map software to find out the approximate direction and height first. If you want to challenge to see Venus directly with the naked eye during the day, you can choose to block the sun with buildings when the east distance of Venus is very clear, and then try to find Venus on the left side of the sun. In addition, the conjunction of Venus and the rarer eclipse of Venus around the moon are also astronomical phenomena worthy of observation and shooting.

To watch Venus, you can choose an astronomical telescope with an optical combination magnified by about 40 times. If there are other options, you can choose a lens with a long focal length or use a Barlow mirror to increase the magnification. Since Venus is very bright, you can use the moon filter to reduce the light.

The surface of Venus in visible light band is not as beautiful as Saturn and Jupiter. Some photographers will use ultraviolet filters to highlight the details of Venus' surface, but ultraviolet filters are not suitable for visual observation.

Fans are mainly concerned about the phase transition of Venus. The phase transition of Venus is also a strong evidence for Galileo to prove Copernicus Heliocentrism. Venus produces phases for the same reason as the moon. From the earth, we can see the different positions where Venus is illuminated, forming a phase. Unlike the moon phase, Venus sometimes forms a circle, and readers can imagine where Venus will produce this phase.

It takes a long time to observe and compare the phases of Venus. Due to the poor atmospheric transparency at the low horizon, enthusiasts who plan to observe need to pay attention to the weather forecast every day.