June 2024 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 June 2024 Star Gazing Guide!
This month marks the start of astronomical summer! Sunset moves back to 9:06 pm while Sunrise bumps up to 5:43 am! This leaves us with only about 8 and 1/2 hours of stargazing time a night in June! So what should we look for? This month we seek the North Star, enjoy a Strawberry Moon and define the Summer Solstice. All this and more you just take some time... to look up.
This month I want you to take a look for a constellation called Ursa Minor, or the Little Dipper. Look to the North and about halfway up the sky you'll be able to find it. In the handle of the Little Dipper or the tail of Ursa Minor there's a special star called Polaris, the North Star. Now Ursa Minor is what we call a circumpolar constellation. That's a fancy word, right? So what does that mean? Remember back in the winter when we could easily spot Orion and how maybe at the beginning of the night it wouldn't be there but would eventually be visible above the Horizon and continue to rise as the night went on? This is because the Earth rotates. That's why the Sun rises and sets as do most of the stars and therefore the constellations that we see. Of course the Stars aren't moving it's actually the Earth that moves, but one star appears to stay in the same place and that star is Polaris the North Star. The North Star is the brightest star that lies directly in line with the geographic North Pole. Because of this Polaris is always at the same latitude above the horizon as we are. In Guelph that would be 43.5 degrees. At the North Pole it would be 90° or directly above you. Now, all the other stars that we see happen to rotate around the North Star because the North Star lies directly in line with our axis of rotation. You've probably seen those cool star trail photos before. So here's the thing, some constellations are so close to Polaris that they never actually set below the Horizon. We call these circumpolar constellations. They're visible all year round and actually all day long and as a result many cultures ascribe significant importance to these constellations whether for navigation or for religious purposes. Circumpolar constellations also depend on where you are on the face of the Earth with respect to latitude. In Guelph Cepheus Cassiopeia and Draco are also circumpolar constellations.
And another thing! Polaris hasn't always been, and won't always be, our North Star! The Earth's axis wobbles as it spins over the course of about 26,000 years. 14,000 years ago our North Star was Vega and it will be again in another 12,000 years!
Our full Moon this month falls at almost the same time as the Summer Solstice with the maximum view of the bright side of the Moon coming just after 9:00 p.m. on June 21st. The Moon may be full but it won't reach as high in the sky in the Summer as it does in the Winter. As a matter of fact it doesn't even rise that night until 9:30 p.m. The Ojibwe of the Great Lakes region call this moon Ode’miin Giizis, the Strawberry Moon, which was also a common name used by settlers and marks a great time to go strawberry picking. The Mohawks call it "the Fruits are Small Moon" while the Cherokee tribes call it “the Green Corn Moon”, both signifying the crops are still young & growing. Our Mi'kmaw friends on the east coast refer to the June full Moon as Nipniku’s the Trees Fully-leafed Moon, while the Cree Nation calls it the Egg Laying Moon, Opiniyawiwipisim, since the wild water-fowl tend to lay eggs at this time of the year.
This year the first day of Summer is June 20th and it's defined by the Summer Solstice. The Earth has an axis that we say it rotates about. It's like an imaginary line that joins the North and the South Poles. It takes 24 hours for one full rotation, which is a day. Now this axis isn't perfectly perpendicular to the plane of our orbit around the Sun. It's actually tipped at 23.5°. The Winter Solstice in December marks a day when the North Pole is actually its furthest distance tipped away from the Sun. The Summer Solstice on June 20th however is the day the North Pole is actually tipped closest towards the Sun and as a result the Northern Hemisphere experiences the most daylight hours that it receives all year long. This is often referred to as the longest day of the year which is kind of confusing because a day only ever has 24 hours. In reality it's actually the day that we experience the most daylight hours in a year. As we head towards Winter, the daylight hours will now start to begin to decrease in length while the nighttime hours will extend for even more stargazing.
Well junior scientists, our summer nights are full of Adventure and all that Adventure is waiting for you up there if you just take some time... to look up.
See you next month Junior scientist 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.