April 2021 Skies

I love April because all of us in the East are back on the same time zone! Daylight Savings ends on Sunday April 4th so our night shows start earlier and that means we can go later.

April 2021 presents three bright planets. Mars is the only bright planet to light up the evening sky. Jupiter and Saturn appear in the morning sky. Venus is hard to see because she sits low at dusk and follows the sun beneath the horizon before darkness falls. Mercury is difficult to view as well, because the solar system’s innermost planet transitions from the morning to evening sky in April 2021.

EMU in the Sky

April is also a great time to try and find the Emu in the Sky.

According to indigenous legends, emus were creator spirits that used to fly and look over and protect the land.

To spot the emu, look south to the Southern Cross; the dark cloud between the stars is the head, while the neck, body and legs are formed from dust lanes stretching across the Milky Way.

While the head and neck of the Emu can be seen in the sky as early as March, it reaches its first appearance in full length after sunset in April and May, when it is seen stretching from the South to the southeast. At this time, the Kamilaroi and Euahlayi people of Northern NSW say the Emu has legs and appears to be running.

The Moon this month

(All times are in Australian Eastern Standard Time)

  • Last quarter Moon:      8:03 pm April 4th
  • New Moon:                    12:31 pm April 12th
  • First Quarter:                 05:00 pm April 20th
  • Full Moon:                      01:32 pm April 27th

Did you know that although the exact date of Easter varies each year, there’s a definite period in which Easter can occur. This period is from March 22nd through to April 25th (in the Gregorian calendar, not the Julian calendar). Easter always occurs on the first Sunday after the Paschal Full Moon. This is the first full moon that occurs after the vernal equinox which signifies the beginning of spring in the northern hemisphere. For us this is the autumnal equinox in the Southern hemisphere.

In 2021, the equinox fell on March 20th, 2021, making the first full moon after that date to be March 28th and the following Sunday therefore is April 4th.

On April 17th in the evening, you will find Mars close to the crescent Moon.

On April 15, at 4am the Moon will be at its furthest point from us (Apogee) for this month being a 406,119 km away.

The full moon on the 27th is a perigee or ‘super’ moon meaning that it will be closer, while at 1am on the 28th it will at its closest approach to us 357,378km away. This is the second closest it will be to us this year – Next month on May 26th we will have a lunar eclipse when the Moon is at it closest for the year a mere 357,311 km away.

Planets in April

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 this 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 the30th 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.

Meteor Showers

Normally a small number of “sporadic” meteors can be seen each hour of a moonless night. Sporadics are likely to be seen in any part of the sky. During a shower, the number of meteors visible may increase considerably. The meteors will appear to originate from a small area of the sky, called the radiant. The spreading out from the radiant is a perspective effect due to the meteors travelling in parallel lines but as they approach the observer they appear to fan out. The shower is named after the constellation which contains the radiant. In general, the meteor trails do not start from the radiant, but a few degrees from it.

Lyrid Meteor Shower

In 2021, the likely peak morning for the Lyrids is Thursday morning, April 22. But the mornings from 19 – 23 should be good, too. The moon is waxing – staying out longer after dark each night – so you will want to watch the time of moonset carefully. The Lyrids are active each year from about April 16 to 25.

Because this shower’s radiant point is so far north on the sky’s dome, the star Vega rises only in the hours before dawn, for you. It’ll be lower in the sky for us in the south so we are best to look out before dawn.

It is named Lyrid because the meteors seem to come from the constellation Lyre.

The Lyrid meteor shower has the distinction of being among the oldest of known meteor showers. Records of this shower go back for some 2,700 years. The ancient Chinese are said to have observed the Lyrid meteors falling like rain in the year 687 B.C. That time period in ancient China, by the way, corresponds with what is called the Spring and Autumn Period (about 771 to 476 B.C.), which tradition associates with the Chinese teacher and philosopher Confucius.

Comet Thatcher (C/1861 G1) is the source of the Lyrid meteors. Every year, in late April, our planet Earth crosses the orbital path of this comet which last visited the inner solar system in 1861,  and is not expected to return until the year 2276.

Pi-Puppid Meteor Shower

The pi Puppids are a meteor shower associated with the comet 26P/Grigg-Skjellerup. The ?-Puppid meteor shower will be active from 15 April to 28 April, producing its peak rate of meteors around 23 April.

The meteor stream was viewable around April 23 but only in years around the parent comet’s perihelion date, the last being in 2003. However, as the planet Jupiter has now perturbed the comet’s perihelion to beyond Earth’s orbit it is uncertain how strong the shower will be in the future.

Sky Views for April

Evening sky view on April 17th at 8pm facing North and West (from Stellarium) showing the crescent moon close to Mars.
Sky view facing East on April 24th at 5am with Jupiter and Saturn (from Stellarium)
Sky view facing East and South on the evening of April 30th at 10pm (from Stellarium) showing the Emu in the sky.

My favourite Dwarf Planet is approaching opposition

On Sunday April 18, 136108 Haumea will reach opposition, when it lies opposite to the Sun in the sky. Lying in the constellation Bootes, it will be visible for much of the night, reaching its highest point in the sky around midnight local time.

From Sydney latitudes it will be visible between 21:26 and 03:53. It will become accessible around 21:26, when it rises to an altitude of 22° above your north-eastern horizon. It will reach its highest point in the sky at 00:40, 40° above your northern horizon. It will become inaccessible around 03:53 when it sinks below 21° above your north-western horizon.

At around the same time that 136108 Haumea passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest.

This happens because when 136108 Haumea lies opposite to the Sun in the sky, the Earth passes between 136108 Haumea and the Sun. The solar system is lined up with 136108 Haumea and the Earth on the same side of the Sun.

Unfortunately, even when it is at its closest point to the Earth, 136108 Haumea is so distant from the Earth that it is not possible to distinguish it as more than a star-like point of light, even through a telescope.

Clear skies until next month! Stay up to date on my Facebook page.

Donna ‘the Astronomer’ Burton