May 2025 Stargazing Guide
Greetings junior scientists, scientists, and citizens of this great big weird, wild and wonderful world in which we live.
As always I'm your humble science communicator, the great Orbax, coming to you from the Department of Physics at the University of Guelph and I'd like to welcome you to our May 2025 star gazing guide.
With April showers behind us here's to a May full of clear dark skies. This month we wake up early for a Venusian sunrise, observe the same lunar phenomena that Leonardo da Vinci saw in the 15th century and try to spot a meteor or two. All this and more while we just take some time...
to look up.
Our planets this month are dim but curious. Venus is visible in the East in the mornings and perhaps best seen for the 2 hours before sunrise on May 31st when it's at its greatest western elongation meaning that it'll be at its furthest distance from the glare of the Sun as observed from Earth.
Saturn is also visible just before a sunrise this month but will be dim, too close to the Sun in its orbit to be seen very well.
Mars and Jupiter are visible in the evenings after sunset. In the West, Jupiter will be dim and low in the horizon making it difficult to see from midmonth onwards.
Mars, the Planet of Robots, will be higher in our sky and will actually pass the Beehive Cluster in the zodiacal constellation of Cancer on May 4th and 5th making for an interesting view with binoculars or a telescope.
This month you'll notice that just after sunset Mars appears alongside two very prominent stars in our sky, Pollux and Castor.
These two stars are the two brightest stars in the constellation Gemini, the Twins.
In Greek mythology Castor was the son of a mortal while Pollux was the son of a god. Other cultures recognize these prominent stars in constellations as well.
The Babylonians called them the Great Twins. The One Who Has Risen From the Underworld and The Mighty King.
Like all zodiacal constellations Gemini lies along the ecliptic and takes up about one 12th or 30° of celestial longitude.
I wanted to talk to you about a unique lunar phenomenon that we have the opportunity to observe this month known as earthshine. The Moon generates no light of its own meaning that when we notice the phases of the Moon we should only see the portion of the Moon that's illuminated by the Sun, like this crescent Moon shown here.
But here's the thing, once in a while we can actually see the surface of the Moon during these waxing and waning crescents. This is known as earthshine or Da Vinci's glow named for the 15th century polymath who theorized its cause.
So how is this possible?
Okay well you know how during a Full Moon, especially in the snowy winter months, your entire yard appears brightly illuminated, right? This is because the Moon is bathing you in the reflected light from the Sun. If you were standing on the Moon instead of in your backyard... in a proper space suit of course... you'd be able to see the Earth dimly lit even though it usually appeared dark as observed from your spot on the Moon.
This is similar to what happens during earthshine.
Reflected light from the Earth bathes the Moon in a slight glow illuminating the craters of its surface. Your best time to observe earthshine is for the few days before or after the New Moon and the effect is strongest in April and May although it can be seen all year long.
The April New Moon occurred on the 27th and our New Moon this month occurs on May 26th.
So if you're looking to see some earthshine try just after sunset for the first few days or the last few days of May, or just before sunrise in the days leading up to May 26th.
Good luck junior scientists.
And speaking of the Full Moon our Full Moon this month is on May 12th and is referred to as the Corn Planting Moon or the Flower moon by many European cultures.
The Mi'kmaw call May’s Moon Sqoljuiku's, the Frog Croaking Moon, named for the sound frogs make when they croak! Squoalch!
The Ojibwe people of the Great Lakes named the May Full Moon Zaagibagaa-giizis or the “Budding Moon”, or “Leafing out Moon” as Mother Earth's healing medicine can once again be found.
The Eta Aquarids meteor shower takes place from April 19th to May 28th as the Earth passes through the dust and debris left by Halley's Comet.
As a matter of fact we experience two annual meteor showers caused by Halley's comet. This celestial ice ball takes about 76 years to make one revolution around the sun and won't be visible from Earth again until 2061.
That second meteor shower that I mentioned is the Orionids occurring in October when we pass through the path of Halley's comet yet again.
The Eta Aquarids are much more active in the southern hemisphere but we can still expect to see upwards of 30 meteors per hour when it peaks in the morning hours of May 6th. The waxing gibbus Moon will light up our sky that night making it difficult to spot these shooting stars but in the early morning hours between 3 and 6:00 a.m you may be lucky enough to spot some meteors appearing to emanate from the constellation Aquarius low in the east.
The universe is ever changing on scales of time and space that may seem like an eternity or change in the blink of an eye.
Our luxury is that we're lucky enough to observe and learn about both.
The beauty and the mystery that makes up our universe is out there just waiting for you to discover it and all you have to do is take some time...
and look up.
See you next month junior scientists and don't forget to have a science-tastic day!
Special thanks to Royal City Science's own planetary geochemist Dr Glynis Perrett for her help preparing our star gazing guide and the Royal Astronomical Society of Canada.