The solar system’s innermost planet can never be seen in the night sky. But there is a chance to see it at twilight during the next two weeks This coming week offers the chance of seeing Mercury in the evening sky. The innermost planet, Mercury’s orbit is just 0.38 times the size of Earth. Being that close to the sun means that we can never see the planet in the night sky but at certain times of the year we can catch a glimpse of it in the twilight. For the next two weeks, Mercury will be visible in the evening as dusk is falling. To see it, a clear south-western horizon will be needed but at least the bright planet Venus is on hand to act as guide. The chart shows the view looking south-west towards Venus at 1730GMT on 3 February. There will be no other stars visible at this time, only Venus and Mercury will shine through the twilight sky. Mercury is much more of a challenge from the southern hemisphere. From Sydney, Australia, Venus will be to the north of Mercury, which just peeps above the western horizon