The starry sky on May 17, 1642

Les planètes visibles à l’œil nu le matin du 18 mai 1642
  • Les planètes visibles à l’œil nu le matin du 18 mai 1642
  • The starry sky on May 18, 1642
The starry sky on May 17, 1642

On May 17, 1642, two French vessels approached the Island of Montréal. On board were Jeanne Mance and Paul de Chomedey, sieur de Maisonneuve, who had come to take possession of the island in order to set up a colony on it. Very early the next morning, the settlers came ashore to begin building this new establishment.

We have to imagine that the intrepid adventurers lifted their eyes to the starry sky that night… But what would they have seen there?

On the evening of May 17, nothing in particular would have caught their attention. The constellation of Leo and its bright star Regulus dominated the western side of the sky, while Gemini was setting on the northwest horizon. Towards the east, the Summer Triangle, made up of the stars Vega, Deneb and Altair, came completely into view above the horizon after 10 p.m., Eastern Standard Time.* The constellation of Scorpio was beginning to rise above the southeastern horizon at sunset, which took place at 7:20 p.m.

The planets in the morning sky

The sky came to life again after 11 p.m., with the rising of the waning Moon. This was four days after the full moon, meaning the lunar globe brightened the rest of the night with its silvery light.

The planets Mars and Jupiter that night were no more than just under four degrees from each other. They rose around 1:45 a.m. to the southeast, followed some twenty minutes later by Saturn. At that moment these three planets found themselves in a portion of the sky lacking a bright star: the constellation Aquarius for Mars and Jupiter, and Pisces for Saturn. They were therefore easy to spot for the first Montrealers – who at the time were called “Montréalistes.” The planet Venus, meanwhile, too close to the Sun at that moment, was not visible.

This first night in Montréal ended with the Sun rising at 4:19 a.m. The Moon, however, until it set at 8:34 a.m., would accompany the settlers when they got off their boats and celebrated their first open-air mass.

Thus was launched a great enterprise, which had very difficult beginnings. But thanks to the perseverance and tenacity of its first settlers, the adventure continues to this day.

Happy 375th anniversary, Montréal!  


At the time, we were living under solar time: the Sun provided the reference point. There was as yet no clock capable of keeping accurate time at sea, much less were there time zones or daylight savings time. The time was always measured locally, in a more or less accurate way. For the purposes of this text, times are expressed according to Eastern Standard Time, which is closest to solar time.


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