Guest Voices-Venus in Transit

Our guest post this week is by Fikiswa Majola, science communicator at the Hartebeesthoek Radio Astronomy Observatory, located near Johannesburg, South Africa.

Moon and Venus at dawn. Credit: NASA

When it comes to observing the night sky, few things are more magnificent to see than the planet Venus. The planet’s beauty and brightness rivals even that of the brightest of stars. After the Sun and the Moon, the planet Venus is the third brightest object in the sky; depending on the time of it is visible, Venus is also referred to as the Morning Star or the Evening Star. In all African cultures there are names for Venus- both as the Morning Star and as the Evening Star, and stories to accompany those. In the Xhosa culture of South Africa, Venus has not two but four names!

The generic name for Venus is iKhwezi, which loosely translates to “one that shines the brightest.” This is a very fitting name, as of all the “stars out there, it does shine the brightest. Venus the morning star is called iKhwezi Lokusa- “one that shines the brightest at dawn.” iKhwezi Lokusa is associated with diligence as it is up before the Sun is.

The second name for Venus is iKhwezi Lesibini– the second Venus. This is Venus during the day. When young boys were out on the fields and herding livestock, one of the games they would play would be to try to spot iKhwezi Lesibini. This game was to test each other’s knowledge of the planet and the sky. Because the Sun is very bright, it would be very difficult to spot iKhwezi Lesibini during the day unless one knew exactly where to look.

Venus the evening star is the most special- it has two names. The first is uCelizapholo, meaning “asking for milk.” This is visible in the evening twilight when it is time to milk the cows. The second name for the evening star is uMadingeni- the dating star. The appearance of uMadingeni represented the time when lovers would rendezvous, away from prying eyes.

There are similar stories about Venus in various other African astronomy tales. In Africa (as was the case around the world), we were observing the night sky since before telescopes. We used the night sky to indicate the time for important events and also to predict things such as drought and the rainy season.

Today I chose to write about Venus not only for its beauty and its significance in the Xhosa culture, but also because it has had the attention of sky-watchers from around the globe in recent weeks. On the 5th and 6th of June many people got a chance to experience a very rare phenomena, the Transit of Venus. A transit of Venus occurs when Venus passes directly between the Sun and the Earth.  This is a very rare alignment that comes in pairs 8 years apart, but separated by over a century. The previous transit was in 2004, and the next is only in 2117. It is unlikely that anybody living today will see the next transit of Venus.

Now what? Are there any more transits in store for us? The answer is yes. The next transit in our solar system will be that of Mercury in May 2016. Mercury is much smaller than Venus and further away, so the transit will not be as spectacular. There are, however, hundreds of significant transits that we observe elsewhere in the universe.

Astronomers use the transit method as one of the methods with which they detect planets orbiting other stars outside of our solar system, exoplanets. These planets can be detected indirectly by studying the slight changes in a star’s brightness; as a planet crosses in front of a star, the observed light from a star will dim slightly.

Transits in our solar system are very rare and Venus itself is something special. iKhwezi– a planet outshining even the brightest of the stars in the night sky. A planet that, even though it’s just the one, can have up to four different names depending on when it is visible. With the transit we said goodbye to the evening star, uMadingeni, and we will soon be greeting iKhwezi Lokusa.