Skywatching

Don't miss Jupiter, Saturn and Mercury shine in a triple-conjunction this weekend

By Joe Rao SPACE.COM

It happens after sunset on Sunday, Jan. 10

Jupiter, Saturn and Mercury will appear near each other in the evening sky shortly after sunset on Jan. 10, 2021 in a dazzling triple-conjunction. 

A spectacular gathering of bright planets will be the chief celestial attraction in the evening sky this weekend as Jupiter, Saturn and Mercury appear to crowd into tight quarters.

Low in the southwestern evening sky just 30 to 45 minutes after sundown, we'll be treated to what might be referred to as a celestial summit meeting, a triple conjunction, with the three planets fitting within a circle smaller than 5 degrees.

Brilliant Jupiter (magnitude –1.9), medium-bright Mercury (-0.9) and dimmer, yellow-white Saturn (+0.6) will be contained within a 5-degree circle from Jan. 8 to Jan. 12, appearing closest together on Sunday evening (Jan. 10).

What will make this array particularly fascinating is how the configuration will change noticeably from one evening to the next. This effect is primarily due to the rapid motion of speedy Mercury relative to the two slow-moving wanderers, Jupiter and Saturn. The pattern will go from a stretched-out triangle on Jan. 8 to an almost equilateral triangle on Jan. 10.

However, binoculars are strongly suggested, as they will help pick up the planets against the bright twilight sky. Jupiter will be at the top of the triangle and is the brightest of the trio, with Mercury and Saturn forming the base angles. The sides of the triangle each measure roughly 2 degrees.

This stunning spectacle might also mark the last evening view of Jupiter and Saturn; while Mercury rises over the coming days, Jupiter and Saturn will be sinking into the sunset fires. While Jupiter and possibly Mercury may be evident without optical aid, Saturn probably will not. In the evenings after Sunday, Saturn will disappear into the bright twilight first, closely followed by Jupiter around mid-month.