Mercury, the closest planet to the Sun, can be seen between Taurus and the Pleiades (or seven sisters) tonight and over the next couple of weeks.
It sits very low in the western sky and is steadily rising to its highest position around 5th/6th May, before dipping down again and fading into June. You should be able to spot it by looking for the bright star of Aldebaran and looking to the right towards the Pleiades, using the naked eye – or get an even better view by using a pair of binoculars or even better, a telescope, eg. such as the Celestron Travel Scope.
First Observations by Telescope
Mercury was first observed through a telescope by Galileo in 1610. At that time, telescopes were not powerful enough to be able to see that the planet actually had phases, just like you can see easily by looking at our Moon. It was not until 30 or so years later, that Giovanni Battista Zupi using a more powerful telescope than Galileo, saw the phases of Mercury for the first time.
The observation of the phases of Mercury proved that Copernicus‘ model of the universe, which stated that the Earth was not the centre of the universe, was correct. Although it mistakingly placed the Sun at the centre of the universe!
Knowledge of Mercury
Most of what we know about Mercury has been gained through the Mariner 10 probe which was launched on November 3rd 1973. It photographed more than half of Mercury’s surface, showing it to have a moon-like appearance: