The transit of Venus - a glimpse of the motion of the Solar System

H.M. Bhushan *

The transit of Venus – a glimpse of the motion of the Solar System

Venus, the brightest object (after the Sun and the Moon) usually observed in the evening or early morning sky will be seen moving across the Sun as a tiny dot as the Sun rises from the eastern direction in the morning of 6th June 2012. This is called the transit of Venus. Astronomically, it means Venus coming in between the Sun and the Earth.

The Alignment in space: The phenomenon requires three bodies to be in a straight line. However, it does not happen every year. The plane (imagine it as a flat surface extended infinitely in all direction with Sun in the middle) in which the Venus revolves around the Sun is inclined to that of the Earth's plane by a small angle 3.39 degree.

The two planes do not coincide. Most of the time, the Venus may be at left or right side of the Earth ie. say some 30 deg or 40 deg with the Sun. It may even be behind the Sun. Even if it comes in between the Sun and the Earth, transit does not take place always, as the planes do not coincide. This makes Venus going around the Sun as seen from the Earth either to move above the Sun or below the Sun ( max. deviation 3.39 deg, Sun's angular size is only 1/2 deg).

The two planes meet in a straight line with Sun in the middle. Now on 6th June, Planet Venus, Earth and Sun will be on this line with Venus in between the Sun and the Earth. The geometry in space can be imagined as the Sun, the size of a football, the two planets, the size of a pea located some 25 feet and 35 feet away respectively from the ball.

Roughly speaking, imagine the ball to be your room, the pea (Venus) in the next room and the other pea (the Earth) in your courtyard. They should be in straight line. Imagine the size and the distance separating them. This is happening on 6th of June 2012 with planets occupying the correct position in space. This makes it a rare astronomical event.

The transit of Mercury also takes place but more frequently than that of Venus because Mercury is in a closer orbit and hence revolves faster thereby increasing the chance of correct alignment. Don't miss this event for it shall not happened again till December 2117, a gap of 105 years.

How to observe: The best is to project to a white screen through a telescope. During 2004 Venus transit, Venus was seen as a very small dot through a six inch reflector with 10 X eyepiece. The screen was placed a little farther away from the eyepiece. Watching directly through Solar filter is OK but Venus might be too small to be observed. Watching without proper eye protection can quickly cause serious and often permanent eye damage.

Significance: Apart from many scientific importance, one will see Venus moving around the Sun, a naked eye visual observation of the motion of Solar System. This will induced in us a spirit of inquiry, a scientific revolution in our mindset.

Watch Venus Transit- through Free Astronomy Software before it actually happened.

Preview of the transit of Venus can be studied through simulation using Astronomy Software before it actually happened, thereby enabling us to gain data regarding time, direction and the path across which Venus will move across the Sun. Astronomy software basically simulates the daytime and nighttime sky as seen from a place defined by its latitude, longitude and the altitude in a computer. It can simulate photorealistic views of the sky.

The Software simulates the sky of a particular time such as current time, past or future sky with correct position of stars, planets, Moon phase, astronomical phenomenon such as eclipses and deep sky objects. Some of them can show comets and artificial satellites as well.

Stellarium is one of the most popular and easy to use free Astronomy software available in the internet. It is downloadable from
http://stellarium.en.softonic.com/.
or
http://sourceforge.net/projects/stellarium/.
You can also search with the key word 'stellarium' in the internet and download.

How to view simulation: After downloading the software, installed it.

Choose your location: Imphal either roughly by clicking on the map given in the menu or by entering position. 24.82°N 93.95°E, alt = 786 m.

Choose date and time: 6th June 2012, before Sunrise, say 2:30 am

Click on the Sun if you find it on the screen with your mouse or (you will find the Sun below horizon if the time you choose is before sunrise) control F 'for search' write Sun and hit enter. It will show the Sun. Hit 'G' to remove 'ground' (place on the Earth where the observer is standing) if you want to. Hit 'A' to remove the effect of atmosphere as transit occurs during daytime at Imphal. Hit 'F' to remove 'fog' around horizon. Hit Space bar to bring the Sun in the centre of the screen and zoom into. Zoom in: Pg up, zoom out: Pg dn.

Now, hit 'L' to increase rate of time simulation. Hitting once is 10 times the real time, twice 100 times, thrice 1000 times and so on. Hitting 'k' will bring it to real time ie. timerate = 1 and hitting 'J' reverse time ie minus time rate. Hitting once is minus 10 times the real time, twice minus 100 times and so on.

Clicking on the Venus and hitting 'O' will show the planet's orbit ie. the path in which venus will cross the Sun. A little exploration and a practice make the software really useful and enjoyable.

The software can be use to study other astronomical phenomenon as well.

Explore,
Wishing you clear skies.

Note: You can watch The transit of Venus at Manipur Univesity or GP Women College, Imphal