Spring ahead to the vernal equinox

THE SUN SETS OVER KEJIMKUJIK LAKE IN NOVA SCOTIA. THE SUN WILL CROSS THE CELESTIAL EQUATOR INTO THE NORTHERN HEMISPHERE ON MARCH 20 AT 1:30 A.M., MARKING THE BEGINNING OF SPRING. (JOHN MCPHEE)

While the bright constellations of winter depart the celestial stage, the star that gives us life will also make a noteworthy transition this month. 

The sun will cross the celestial equator from the southern hemisphere to the northern half on March 20 at 1:30 a.m. ADT - the vernal equinox

Of course, the sun isn't actually moving - we are. As the Earth zips around our home star, different parts of the planet get more or less sunlight at various points in that orbit.

SEE ALSO: March skylights

That's because the Earth's spin is a little crooked - it's tilted 23.5 degrees compared to the plane of our orbit. 

From late March onward, we northerners get the benefit of the tilt, while the sunlight begins to fall more directly on the southern hemisphere in September. 

Earth isn't the only off-kilter planet in our system. On the extreme end is the cold gas giant Uranus, which rotates virtually sideways in space at 82 degrees, according to NASA's website on weather in the solar system. 

But another gas giant, Jupiter, is tilted only three degrees. And Jupiter's spin isn't only super straight, it's super fast.  The planet whirls around so quickly that its poles are slightly flattened.

Jupiter has moved into prime viewing position in the evening sky this month, after being part of the planetary party at dawn last month. It's high in the southeast by 10 p.m. in Nova Scotia in the constellation Leo.

Even a small telescope will reveal the faint cloud bands that wrap around this gas giant. You’ll also notice dots of light around the planet, which are Jupiter’s largest moons. 

I took this photo on Feb. 23,  2016, when all four of Jupiter's Galilean moons were visible. 

You’ll often see all four of the “Galilean” moons Callisto, Io, Europa and Ganymede, which are named after the Italian astronomer who first saw them in his crude 8x telescope in either December 1609 or January 1610.

Turning our gaze out beyond our solar system, we see the changing of the guard from the winter showpieces of Orion, Canis Major and Taurus to the more subtle spring constellations.

Leo the Lion leads the charge in the east ‐ this rather faint constellation is easier to locate than usual. As noted above, this month it encompasses the planet Jupiter, the third brightest object in the night sky after the moon and Venus.   Above Jupiter is the brightest star in Leo, the blue‐white Regulus, which marks the bottom of the constellation's trademark reverse question‐mark.

The much brighter Arcturus marks the otherwise dim constellation Bootes (buh‐OH‐teez) to the east of Leo. When you see this striking rusty star rise in the evening, you know winter's days are numbered.