A celestial spectacle awaits the early riser who wishes to gaze out at the pre-dawn skies. It is the apparent alignment of four of the brightest planets — Venus, Mars, Saturn and Jupiter — in a line. This year, the planets will appear close in the months of April and May. As they move along in their orbits, Saturn will get further away from the others, while Jupiter and Venus will appear really close on May 1, and Jupiter and Mars will look closer on May 29.
The four planets can be seen in the eastern sky before sunrise, from close to 4 a.m. to before sunrise. They are bright so can also be seen in early twilight. “At this time, the planets in order of position from east to west, that is, from the horizon upwards, are Jupiter, Venus, Mars and Saturn,” explains Niruj Mohan Ramanujam, the head of the Science Communication, Public Outreach and Education (SCOPE) section of Indian Institute of Astrophysics, Bengaluru.
Actual distances still vast
The four planets appear in a line at this moment in the morning, and as they move in their orbits, some of them can get quite close to one another in the sky. However, this is just an apparent alignment as seen from our perspective on Earth. The actual distances between them are still vast. “This is an excellent occasion for all of us to visually track the positions of these fast-moving planets every day, and appreciate the motivation of all ancient cultures to understand and predict their paths in the sky,” said Dr. Ramanujam.
Since the planets appear close, we on Earth now have a reference against which to observe the motion of these fast-moving planets.
“Because this is an apparent alignment in the sky, this will have no effect on the Earth, or on humans,” he added.
How is it that the four planets that are widely separated in space appear to be in a row? “All the planets move around the Sun in very roughly the same plane, and therefore, their paths on the sky fall within a narrow band, around the ‘Ecliptic’. Because of this, we can see some planets apparently being close together in the sky from time to time,” he explained.