Saturn, Mars, Venus and Jupiter are set to line up neatly in the pre-dawn sky later this month in a rare celestial spectacle, astronomers say. Starting April 17, the four planets will appear diagonally, with Jupiter nearest the horizon and Saturn the highest. In the northern hemisphere, they’ll be most visible in the south-east on April 20, just next to the sun rising in the east, although Jupiter might be obscured by the light of the sun until the last week of the month. In the southern hemisphere, the planets will be visible at the same time of the month but further east and at a steeper angle. Joining the four planets in their neat line in the last week of April will be the moon, appearing further south, just right of Saturn. An alignment does not mean that these planets will overlap each other or come extremely close to each other, they will still be separated by billions of kilometers in the vastness of space. The alignment is the result of our orientation with respect to these planets as their views change from month to month as Earth rotates in its orbit around the Sun.