All Things Being Equal
Perched above the equator, the sun splits the day between light and dark
As darkness settles, Venus and Jupiter blaze in the west, and with the moon absent there is no brighter objects visible. After drawing together for weeks, Venus has pulled ahead. At week’s end they are four degrees apart, and the distance grows by about a half-degree each night. Both planets are climbing higher into view, heading from Aries toward Taurus and the Pleiades star cluster.
Opposite Venus and Jupiter, Mars burns a fiery orange above the east horizon. By midnight the red planet is high in the south, while it dips westward in the pre-dawn hours, finally setting in the west around 6am. Don’t confuse Mars with Regulus, dimmer and a twinkling blue-white, 10 degrees higher.
A little after 9pm, Saturn rises in the east, but its golden glow is no brighter than a strong star, as you can see compared to Spica, six degrees ahead along the ecliptic.
The ecliptic is the imaginary path traveled by the sun, moon and planets as they “circle” the earth. While science long ago disproved the notion that earth sits central to the celestial objects revolving around us, the ecliptic remains central to astronomy as well as earth’s seasons.
This week on Tuesday, March 20, the sun’s place along the ecliptic intersects with another symbolic line, the cellestial equator, an extension skyward of earth’s equtor. Hovering directly above the equator, the sun sheds its light equally between the two hemispheres with night and day divided equally in two.
For us in the Northern Hemisphere, this marks the vernal equinox, the first day of spring. Hereafter, the sun will peak farther and farther north of the equator, bathing us in more sunlight each day until the summer solstice, when the sun hovers its farthest point north above the Tropic of Cancer.