Spot the Straight Line by Planets this week.

April 21, 2022

This month, as the Sun sets in the evening, we can notice the 3 stars that form a straight line, which most of us are familiar with. This is Orion’s belt and can be easily identified without knowing much of Astronomy. However, this month, a celestial treat is at display in the morning skies. If you venture out after 4.30am in the morning, you’ll notice, near the eastern horizon, 4 bright dots in the sky forming a straight line, just like Orion’s belt, but larger. These are the 4 planets Saturn, Mars, Venus and Jupiter respectively from top.

The Alignment

As the Earth moves around the Sun, we can imagine a plane of this orbit which we call Ecliptic. From the laws of physics, all the planets orbit the Sun, forming such planes which are practically similar. The Moon also moves around the Earth on a plane that is very close to the ecliptic plane and is tilted by just 5 degrees.
When we observe the celestial objects from Earth, as the Earth moves around the Sun, the Sun seems to trace a path across the sky, with respect to the background stars, which form the Zodiac constellations. As the Sun moves across the sky, the planets and the Moon also seem to follow a similar path along the ecliptic, although not exactly the same. Therefore, when viewed from Earth, as the planets move around the Sun at various speeds, they seem to come together and move away from each other, giving us planetary conjunctions and oppositions.

When and Where?

Currently, apart from Mercury, the 4 visible planets are all on the west of the Sun and are close enough to seen in a straight line. The ringed planet Saturn rises around 2am, followed by the red planet Mars which appears around 3am. Currently the Morning star, Venus, appears above the horizon around 3.30am and the largest planet, Jupiter completes the train as it rises at 4am from the Eastern horizon. The 4 planets will have risen sufficiently high around 4.30 for everyone to notice the straight line.

The Moon will join them on the 24th of April giving us 5 celestial objects in a straight line.

The planets will be visible in this configuration in the coming months as they slowly drift apart. Venus is currently moving towards the Eastern horizon with each passing day, while the other three planets appear to move towards west. Jupiter will meet Venus on the 1st of May this year as they appear just 0.25 degrees apart. Jupiter will then overtake Venus and move towards Mars, in this configuration.

Are they really one behind the other?

While these planets appear close to each other in the sky, they are located at various distances from us. Saturn is currently over 150 crore kms away from us, while Jupiter is 86 crore kms away, while the planets Mars and Venus are 25 crore kms and 13 crore kms away respectively.

Therefore, this celestial phenomenon is merely the planets moving around the Sun at their own speeds and appearing to be in a single line, but the sight is something every amateur astronomer would rejoice, looking at. PAAC wishes everyone clear morning skies to enjoy this planetary alignment and the celestial phenomenon this month.

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