Earliest spring equinox in 124 years brings planetary entertainment
If you're stuck at home this week during the coronavirus outbreak, the planets and our moon are providing some early morning entertainment. Mars, Jupiter, Saturn and a crescent moon will be clustered together in the southeastern sky just before daybreak. Mercury will peek above the horizon.
All this is happening amid the earliest March equinox in 124 years.
The vernal equinox, which marks the beginning of spring in the Northern Hemisphere - and autumn in the Southern Hemisphere - will occur late Thursday night in the U.S. That's the earliest since 1896.
This is also a good time to spot Sirius, the brightest star in our night sky. Barely 8.6 light-years away, Sirius is especially brilliant this time of year. It's also known as the Dog Star because it's in the Canis Major constellation.
To spot Sirius, find Orion in the southern sky and follow Orion's belt. The three stars making up the belt point toward Sirius, downward in the Northern Hemisphere and upward in the Southern Hemisphere.
What is the spring equinox?
The word equinox comes from the Latin words -aequus (equal) and nox (night) meaning "equal night." As CBS Boston reports, on the equinox, the length of day and night is nearly equal in all parts of the world. During this time, earth's two hemispheres receive the sun's rays about equally.
Equinoxes are the only two times a year that the sun rises due east and sets due west for all of us on Earth. If you were standing on the equator, the sun would pass directly overhead on its way north.
During the spring equinox, the sun passes overhead, and the tilt of the earth, which is tilted on its axis by about 23.5 degrees, is zero relative to the sun, which means that earth's axis neither points toward nor away from the sun. After the spring equinox, the northern hemisphere tilts toward the sun. This is why we start to see longer periods of daylight, in turn; it gets warmer with more sunshine throughout the day.