December 21, 2020: On Winter Solstice morning, brilliant Venus is low in the southeast before sunrise. Antares is near is annual heliacal rising.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:15 a.m. CST; Sunset, 4:23 p.m. CST. Check local sources for sunrise and sunset times for your location.
The sun makes its lowest arc across the sky today, rising and setting at its farthest south points. The sun’s rising and setting points slowly move northward along the horizon and the diurnal arc of the sun increases in height after today. The sun’s celestial coordinates place it at a point known as the winter solstice. The sun is 270° from its location on the first day of spring – the Vernal Equinox.
Astronomically, this is the first day of winter (in the Northern Hemisphere), beginning when the sun’s celestial coordinate is 270° at 4.02 a.m. CST.
As the sky brightens this morning, Venus is low in the southeast. It is slowly slipping back into the sun’s glare.
The star Antares is making its first morning appearance (heliacal rising) this week. If you have a clear horizon to the southeast, Antares is very low in the sky. A binocular helps. During the next few mornings, the star becomes visible without the help of a binocular.
Predicting heliacal rising dates is tricky. They occur when the star is at a threshold altitude above the horizon about 45 minutes before sunrise. A clear sky without any clouds or haze to the natural horizon is needed. The first observed date depends on the individual’s location and the weather.
This occurred with Sirius last summer. This writer observed Sirius with a binocular for a few mornings as clouds moved in and out of the region where the star appeared. Then one morning it is visible without the help of optics after a cloudy morning.
Detailed Note: The winter solstice occurs at 4:02 a.m. CST. Forty-five minutes before sunrise, Venus is less than 10° up in the southeast, 3.8° to the lower left of β Sco and 0.7° to the right of Psi Scorpii (ψ Sco, m = 4.5). Use a binocular to see the star. This morning’s test is whether Antares is visible. Venus is 6.2° to the upper left of Antares (α Sco, m =1.0). The star is less than 4° in altitude. You’ll need exceptional observing conditions and a binocular to see it.
Read more about the planets during December.
November 7, 2021: During the early evening Venus and the moon group together in the southwest.
November 6, 2021: The midpoint of Autumn occurs today.
November 3, 2021: Before sunrise speedy planet Mercury, the crescent moon, and the star Spica are grouped together. The trio does not appear this close together again until 2033.
October 31, 2021: There is no Halloween Full moon this year, and the phase is not close. The crescent moon is in the morning sky. Mercury is low in the east-southeast before sunrise. The planet pack – Venus, Saturn, and Jupiter – gleam in the evening sky.
October 29, 2021: Venus reaches its greatest elongation from the sun. It is in the evening sky with Jupiter and Saturn. The crescent moon and Mercury are in the eastern sky before sunrise.