The brightest planet in the solar system, Venus, shines like an incredibly attractive diamond on the soft velvet of the evening twilight. Among all the celestial bodies, it is second only to the Sun and the Moon in brilliance. The Evening Star catches the eyes of even those who rarely look up to the sky. And on Christmas Eve, it will be the first star to appear in the sky. Why is it so bright? And how long will it be visible in the evenings?
How did our ancestors see Venus?
Since ancient times, Venus has been known as the “Morning Star” or “Evening Star”, and although most ancient peoples considered them different objects, there is evidence that as early as 3-4 millennia ago, the Sumerians and Greeks mentioned them in their records as the same luminary. The most developed civilizations of Babylon, Mesoamerica (Maya), Ancient Greece and Egypt paid special attention to Venus, endowing it with supernatural properties and trying to use its movement to predict fate.
The planet’s attractive appearance was identified with the goddesses of beauty, love, rebirth, and motherhood. For Muslims, it was a symbol of beauty, the Greeks called it Aphrodite, and the Romans called it Venus. Over time, it was the latter name that took hold, and the planet second from the Sun became the only one to be named after a goddess. After all, the brightest planet is the right one to personify the patroness of the strongest feeling – love.
There is an assumption that Babylonian astronomers knew about the changing phases of Venus, and this made her the “sister of the Moon”. However, today this thesis is seriously questioned. In any case, it was only in 1610 that Galileo Galilei, who made observations with a small telescope, was able to see the crescent of Venus reliably. This feature of the planet was a powerful evidence in favor of the heliocentric system of the world.
Why is Venus so bright?
In the Earth’s sky, Venus takes the third place in terms of brightness, right after the Sun and the Moon. Its luminosity can reach -4.9m, and at this time it is 23 times brighter than Sirius, and almost 22300 times brighter than the faintest stars visible in the dark sky with the naked eye.
It would seem that Jupiter, the largest planet in the solar system, should get the “palm branch”. But it is much further away from us than Venus. And this is not the only factor due to which the giant is inferior to the “infernal sister of the Earth” in brilliance.
Being 7.2 times farther from the Sun, Jupiter receives 52 times less light from it. In addition, Venus is shrouded in lower clouds with a very high albedo – it reflects 76% of sunlight, while Jupiter reflects only 34%. In fact, this beauty is the first of all the planets here as well: it has the highest reflectivity.
Source: The Planetary Society.
Now, in mid-December 2024, Venus is gradually approaching us, but its phase – the illuminated part visible from Earth – is decreasing. On January 10, 2025, the planet will be at its greatest eastern elongation. This means that it will be visible in the evening sky, and the angular distance between it and the Sun will reach the maximum possible 47.2° on that day. For an Earth observer armed with a telescope or binoculars, the planet will look like a tiny Moon, illuminated by 51%. Does this mean that Venus is the brightest at the moment of greatest elongation?
Strangely enough, this is not the case. After January 10, Venus will continue to approach the Earth. At the same time, two processes are occurring simultaneously: on the one hand, the angular size of the planet is growing, and on the other hand, the crescent illuminated by the Sun is thinning. Which of these phenomena “wins”? Up to a certain point, it is the increase in apparent size. If now the brightness of Venus is -4.3m, then on January 17-19 it will reach the maximum possible value of -4.9m, that is, it will become 1.7 times brighter.
When and how to observe the Evening Star in the near future?
At the moment, Venus is easy to find in the evening sky with the naked eye. Immediately after sunset, it is located about 17° above the southern (and a little later – slightly lower above the southwestern) horizon. So, to admire the “Queen of the Evening”, it is enough to choose a place of observation so that the corresponding side of the world is accessible.
During December and January, the planet’s visibility will only improve: it will rise higher and higher above the horizon, and, as mentioned above, will reach its peak brightness on January 17-19. In February, Venus will gradually begin to approach the Sun, accelerating its run in March until it is in its lowest conjunction on the 23rd, positioned almost exactly between the Earth and the Sun. A few weeks after that, in April, you can try to catch it as the Morning Star low over the eastern horizon, just before sunrise.
Photo: Yuri Beletsky.
Although Venus is aesthetically pleasing even when viewed with the naked eye, observing it through a telescope will bring special emotions. Even with a small instrument, you can see that the planet does not look round, and by tracking it for weeks, you can see how the phases change and the angular size of the crescent increases. In the dark sky, it is more difficult to distinguish the shape due to the extremely high brightness of the object. Therefore, the best time to observe with a telescope or binoculars is when the Sun has just disappeared behind the horizon.
Few people know that Venus is the only planet that can be seen with the naked eye even during the day. And the best time for such “exercises” is during the weeks near its maximum elongation. During your first attempts at such observations, you will face some difficulties. First of all, without distant stars in the sky, it will be difficult to navigate the sky to determine where to look. We recommend using interactive mobile planetarium apps that show the position of the stars in the sky according to the orientation of your phone or tablet. The second problem will be focusing your vision – it needs to be “adjusted” to infinity, and we almost never need this skill in everyday life.
Here are some tips. Try to memorize the sensations in your eyes when you look into infinity – at the distant stars – in the night sky, and then recreate this state during daytime observations. You can also practice finding Venus in the evening sky earlier and earlier each day relative to sunset. Start by observing it when it is already below the horizon, then try again when the day star has not yet completely disappeared, until you gradually get to real daytime observations. It’s certainly a rather exotic exercise, but you can take to the bank, your efforts will be more than rewarded when one day you manage to “catch” this tiny star in a completely bright sky.
