Planets in April 2021

Planets in April 2021

Mercury

Is low in the morning sky this month and lost in twilight mid-month. It is not easy to see this month, as it transitions from the morning to evening sky. On the 1st Mercury was a hand-span above the eastern horizon an hour before sunrise and in line with Jupiter and Saturn.

On the 11th the thin crescent Moon was just above Mercury low in the twilight, 30 minutes before sunrise. You will need a level unobscured horizon and possibly binoculars to see this.  

By the 15th Mercury is lost in the twilight. Mercury swings to superior conjunction (see diagram below) on April 19, 2021, to enter the evening sky.

After that, Mercury will climb away from the sunset, to reach its greatest eastern (evening) elongation from the setting sun on May 17, 2021.

Mercury’s mean distance from the sun is about 0.39 times Earth’s distance from the sun. In the above image we are looking down from the north side of the solar system plane, in which case Mercury and Earth circle the sun in a counter clockwise direction.

Venus

Is lost in the sunlight and we will need to wait until May when it will return to the evening sky.

Mars

Is visible low in the western evening sky. even though it is starting to dim as it is long past opposition. Mars can be found in Taurus – between the two horns of the bull.

On the 13th Mars is almost directly between Elnath and Zeta Tauri, which form the tip of the other horn. On the 15th Mars is above the north-western horizon an hour and a half after sunset.

On the evening of the 17th the crescent Moon is very close to Mars. Mars passes through the outskirts of the open cluster M35 on the 27th. You will need binoculars to see the encounter at its best.

On the 30th Mars will still be above the north-western horizon an hour and a half after sunset.

Jupiter

Is rising in the morning eastern twilight sky and is becoming much easier and brighter to see.

Rising in the morning eastern twilight sky and quite easy to see. It starts the month in Capricorn and then slips into Aquarius.

At the start of the month it is in a line with Mercury and Saturn. On the 15th Jupiter is quite high above the north-eastern horizon an hour and a half before sunrise.

In either binoculars or a telescope Jupiter’s Moons are always interesting. Jupiter is now high enough to follow the moons dance.

Saturn

Like Jupiter is now rising higher in the morning sky. You will find it as a yellow star like object above Jupiter.

On April 1 Saturn is well above the eastern horizon an hour before sunrise. At this time it is in a line with Mercury and Jupiter.

By April 15, Saturn is much higher above the eastern horizon an hour and a half before sunrise.

On the 30th Saturn high above the eastern horizon an hour and a half before sunrise and still in a line with Jupiter.

Uranus

Is no longer visible and will remain in Aries until 2024 when it will move into Taurus. It will disappear from view as it moves towards conjunction in early May.

Neptune

Returns to the morning sky in Aquarius as it passed through conjunction with the Sun late last month.

Donna the Astronomer

I am a keen astronomer lucky enough to live and work in Coonabarabran the Astronomy Capital of Australia! I am a ‘Drover’s Brat’ and discoverer of a couple of comets and asteroids. I operate Milroy Observatory and can show you how to best integrate dark sky experiences into your tourism, farm stay or AirBnB business.

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