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June 2022 Sky Notes

Many thanks to our colleague John Flannery for providing the below information on what to watch out for in the skies this month! John is a long-time amateur astronomer with an interest in the history and lore of the sky. He is a member of the Irish Astronomical Society.

A parade of planets not repeated until the end of this century warrants an early rise at least one morning this month.

A parade of planets

An unusual celestial sight in the morning sky greets the dedicated observer during the latter half of June. Early risers will see Mercury through to Saturn lined up in the same sequence as they are in the solar system.

That does not happen often and the same arrangement is next not easily visible from here until May 2100.

The gathering is already evident from lower latitudes, but Mercury stubbornly remains too deep in twilight until mid-June for us.

Your first glimpse of Mercury might be around 4:15am on June 17th after the beginning of civil twilight but the planet is then still exceptionally low and easy to miss.

It is far better to wait another couple of days when Mercury appears over the northeast horizon a little earlier and brightens more. By the 20th, Mercury is rising at 4am and an hour before the Sun.

The next day, Jupiter is to the upper left of the first quarter moon, which passes the planets over the next few mornings as it wanes.

All the worlds now appear like pearls strung along the line of the ecliptic, the path of the Sun through the zodiacal constellations, and the course followed by the planets.

Saturn, rising not long after midnight towards the end of June, lies in in Capricornus. The rings are at their minimum inclination for the year this month but still show beautifully in a telescope. Their aspect is narrowing though, and the rings appear edge on to Earth in 2025 when we pass through their plane. 

On the 22nd, the moon lies between Jupiter and fainter Mars. Both, being further out, are slower moving than Venus, which is a dazzling lamp hung over the skyline.

Venus slips below the Pleiades star cluster in Taurus on June 24th and both should squeeze into the same field of view as lower power binoculars.

Two days later, on the 26th, the crescent moon is close to Venus and makes a beautiful pairing to enhance the already marvellous dawn scene.

On the 27th, the slender moon is just above Mercury. If you have not yet managed to spy the innermost world, then now is your chance as the two are in the same binocular field of view. The last few days of the month are also when Mercury is reaching its brightest for this apparition. 

Mercury only sticks around until the first couple of days of July though before it plunges back into the solar glare and brings down the curtain on the performance.

Our connection to the cosmos is apparent on the morning July 1st as the International Space Station takes eight minutes to glide from right to left below the planets from 3:50am. What a family portrait that would make! You can get predictions of the pass for your location from the Heavens Above website. 

The morning scene this month encompasses not just the classical naked-eye planets but Uranus and Neptune too. The former is in Aries, between Mars and Venus, while the latter is in Pisces. Both ice giants are visible in binoculars with the aid of a planetarium app charting their position.

Opportunities like this to see all the Sun’s family in one sweep only arise when for a few years Jupiter and Saturn are not too far apart either side of their once-in-twenty-year Great Conjunction’s.

The last of those tight pairings occurred in December 2020 and the previous July afforded the chance to see the planet procession, although their sequence was different from this month’s remarkable spectacle.

Historically, planetary conjunctions of this type triggered the usual predictions of doom.

Almanacs of the time proclaimed a great Flood and broadsheets warned of the end of the World when all five naked-eye planets fitted in a ten-degree wide circle (twenty full moon diameters) in February 1524.

More recently, the planets bunched up in May 2000, leading to dire predictions of earthquakes and tsunamis being raised on Earth due to all the other bodies in the solar system tugging on our planet.

Yet again, we passed that doomsday without any ill effects. In fact, the gravitational pull acting on you from a large aircraft flying overhead is greater than that of all the planets combined!

Looking ahead, circle December 13th, 9606 in your diary. A handspan covers all the planets from Mercury to Uranus on that date.

By then, who knows how far humankind will have travelled from Earth. Perhaps a similar conjunction will be witnessed from one of the 5000 known extrasolar planets by our descendants who will call a different world home.


The moon in June

Full moon on June 14th is the second of four so-called supermoons in 2022. The closest full moon of the year will be next months.

Notice the moon’s height when it is due south on the night of the 14th. June is when the full moon always travels lowest across the sky as its path then generally mirrors that of the Sun in December.

An extra factor though is the tilt of the moon’s orbit with respect to Earth’s equator. Over an 18.6-year period that obliqueness – and the timing of the phase – gives rise to a difference in the full moon’s maximum altitude around the summer solstice.

The extreme values are due to a phenomenon known as a major or minor lunar standstill.

The next major standstill is in 2025 when June’s full moon appears a little lower in the sky than this year’s. I recall the last event in 2006 when I had a hard job finding the golden orb as it played hide-and-seek behind the neighbouring houses.

First quarter moon is on June 7th, last quarter on the 21st, while new moon is on June 29th.


Clouds at the edge of space

Despite the gloomy start to June, observers have already recorded the first sightings from Ireland of cirrus-like noctilucent clouds (NLCs.)

Wisps may appear at any time above the northern skyline between now and mid-July from about 90 minutes after sunset or as the sky lightens before sunrise. They can persist throughout the night and brighten or fade in intensity as well as show structural changes over a short space of time. 

NLCs form around 80 kilometres up when temperatures in the mesosphere fall below -120 degrees Celsius and ice crystals condense on tiny particles composed mostly of micrometeor dust.

Their great height allow the silvery threads to glisten in the sunlight while the world below is in darkness. Displays are most frequent from higher-latitude temperate regions but have also appeared as far south as Los Angeles.

Martin McKenna and Stephen Cheatley both have extensive information on their websites about viewing and photographing NLCs. Observers also post sightings over the northern hemisphere summer months to @NLCalerts on Twitter.