After an April marked by the astronomical event of the century in Montreal, the May sky is slated to be much calmer... although we may be treated to a fireworks show.
The planets play hide-and-seek
It’s a period of extreme drought for evening planetary observations, what with Jupiter lost in the glow of the setting Sun at the start of May and in solar conjunction on the 18th. Saturn won’t be visible before midnight until at least August.
In May, the timid planets will only be visible in the early morning hours. Starting with Saturn (magnitude +1.2), which rises increasingly earlier (3:45 a.m. on May 1st and 2 a.m. on the 31st), allowing it to reach an altitude of 24 degrees above the southeastern horizon, just as civil dawn begins by month’s end.
Saturn gradually falls behind Mars (magnitude +1.1). In early May, the Red Planet is 14 degrees to the left and slightly lower than the Ringed Planet, but the gap rapidly widens to 34 degrees by the end of the month. A better time to observe the Red Planet will be towards the end of May, when it rises at 3 a.m. and reaches a height of 15 degrees above the eastern horizon at the break of civil dawn.
The Moon will join the two planets at the start and end of the month. On the morning of May 3, the last crescent Moon can be found 8 degrees to the right of Saturn. The next morning, May 4, the ever-thinner lunar crescent lies between Mars and Saturn. Then, on the morning of May 5, the very thin crescent Moon hangs 5 degrees to the left of the Red Planet. One lunar cycle later, on the morning of May 31, our natural satellite once again swings by Saturn, just one degree below the ringed planet!
Moon meets stars
On the night of May 17-18, the waxing gibbous Moon occults Beta Virginis, a relatively bright star (magnitude +3.6) in the constellation Virgo. In Montreal, the star disappears at 1:23:47 a.m. (EDT) behind the Moon’s dark limb: The action takes place 18 degrees high in the west-southwest. It reappears at 2:28:03 EDT from behind our satellite’s illuminated edge, but is more difficult to observe since it takes place very low on the western horizon, a mere 7 degrees high.
A remarkable fact about the May 23 full moon: As it emerges above the southeastern horizon at around 9:30 p.m., the Moon will lie less than 1/10th of a degree from the brilliant star Antares, a red supergiant in the constellation Scorpius. This proximity makes it easy to observe the Moon’s movement relative to the stars—on the right to begin with and then, barely an hour later, below the reddish star. Note that for observers in the Caribbean, eastern South America or western Central Africa, this meetup won’t be a simple conjunction, but an occultation of Antares by our humble Moon.
Eta Aquarids, an exceptional year that proves the rule?
Like every year, the Eta Aquarids meteor shower peaks around May 5. Although not as well known in the Northern Hemisphere, this shower is nevertheless the third strongest of the year, after the Geminids and the Perseids. The angle at which the Earth’s orbit and the meteor stream intersect, however, favours observers in the Southern Hemisphere, who can usually expect to see up to 60 or 70 meteors per hour in perfect conditions, compared with just 15 or 20 at our northern latitudes.
But things could be different this year. If the prediction by Auriane Egal (science advisor at the Planetarium and a specialist in the observation and modelling of meteor showers) is confirmed, the Eta Aquarids activity level in 2024 could be three times higher than usual and, above all, richer in exceptionally bright meteors called “fireballs.”
In a scientific publication analyzing the activity of the Eta Aquarids over the last few decades, Auriane presents recent data that point to occasional outbursts in the number of meteors observed at this shower’s peak. Such outbursts, noted in 2004 and again in 2013, can be explained by Jupiter’s gravitational influence on the varying concentration of meteoroids along their trajectory. But as Auriane points out, more observations are needed to confirm this periodicity, so this year will be particularly important!
Meteor showers occur when Earth passes through parts of its orbit that cross streams of debris—dust and small rocks called meteoroids—left behind by a comet or asteroid. In the case of the Eta Aquarids, the famous Halley’s Comet is the parent body.
Observers can admire these fragments of Halley’s Comet that disintegrate as they plunge into our atmosphere by gazing skyward in the hours just before sunrise between May 4 and 8. The radiant of this meteor shower lies in the constellation Aquarius, low in the southeast and not far from Saturn, Mars and the Moon on those May mornings. But the best way to watch shooting stars is to ensure you have the widest possible field of view, looking towards the zenith.
Meteor detection networks and one highly interested observer will certainly be checking to see if the much-anticipated fireworks materialize.
