2021, March: Mars in Taurus
March 2021: While not as bright as a few months ago, Mars marches eastward through the starfields of Taurus during the month. Use a binocular to watch it skip past the Pleiades star cluster and near the Hyades. Later in the month, it passes Aldebaran, the constellation’s brightest star, and moves toward the Bull’s horns as the month ends.
By Jeffrey L. Hunt
After a few months moving through dim starfields, Mars marches through the richer background of the stars of Taurus.
Mars is dimming as Earth moves farther away from the planet after the Mars opposition during October 2020.
Read more about the planets during March 2021.
Locate the Pleiades star cluster. Find the stars nearly two-thirds of the way up in the sky above the west-southwest horizon. The individual stars are not bright alone, yet when packed together they attract one’s attention. Together, they resemble a tiny dipper (not to be confused with the Little Dipper) or a bunch of grapes. Mars is the reddish star nearby. Do not confuse it with the star Aldebaran, the brightest star in Taurus.
Mars last passed Aldebaran on April 14, 2019. After this month’s march through the starfield, the planet returns for a triple conjunction with Aldebaran during the fall of 2022 and early winter of 2023.
This year’s passage through the constellation is easily observed, whether with unaided eyes or through a binocular.
A telescope’s field of view is too limited and the star clusters seem to spill out the edges of the view. The Hyades star cluster and Pleiades star cluster are too large to fit in the telescope’s eyepiece, even at its very lowest power.
A binocular may reveal a few dozen stars in the Pleiades star cluster, although during the unaided view, one may see six or seven stars. This star cluster is frequently named the “Seven Sisters.”
Use the same binocular that is used for sporting events or bird watching. Lower power, such as 7x, are more easily steadied than a binocular of higher magnification. (A 7×50 binocular magnifies 7x and has 50 mm diameter lenses in the front.) Unlike the perspective shown in the movies with two circles of light, your eyes see one circle as portrayed in some of the charts that follow.)
Photographers can capture Mars with the Pleiades and the Hyades with a tripod-mounted camera and exposures up to 20 seconds, depending on the focal length of the camera lens and the local lighting conditions.
Begin looking for Mars about one hour after sunset. It sets in the west-northwest around midnight.
Here’s what to look for (Unless noted, times for the daily notes are for one hour after sunset.):
- March 1: One hour after sunset, Mars is over two-thirds of the way up in the sky above the southwest horizon. The Red Planet is 3.0° to the lower left of Alcyone (η Tau on the star chart above), the brightest star in the Pleiades star cluster.
- March 4: One hour after sunset, Mars is less than 60° up in the west-southwest, 2.6° to the lower left of Alcyone, as the Red Planet passes the star this evening.
- March 7: Nearly two-thirds of the way up in the west-southwest as night falls, Mars passes 0.5° to the left of 32 Tauri (32 Tau). Use your binocular.
- March 8: One hour after sunset. Mars, high in the west-southwestern sky, is well-past the Pleiades, 3.6° to the upper left of Alcyone. The planet is below a line from Alcyone to Aldebaran, 10.0° to the lower right of the constellation’s brightest star. Among the dimmer stars, use a binocular to spot 37 Tau 0.9° to the upper left of Mars.
- March 9: Mars – less than two-thirds of the way up in the west-southwest at nightfall – passes 0.3° to the lower right of 37 Tauri (37 Tau).
- March 13: One hour after sunset in the west-southwest, Mars passes 7.2° to the upper right of Gamma Tauri (γ Tau). The star is in the Hyades star cluster and at the bottom of the “V” that makes the Head of the Bull. Because the coordinate system is angled from upper right to lower left, Mars’ conjunctions (closest points and shared celestial longitude) occur when the planet appears to be well-past the star compared to their positions in the western sky.
- March 14: Less than two-thirds of the way up in the west-southwest, Mars passes 2.2° to the upper right of Omega Tauri (ω Tau). The planet is below a line that connects Aldebaran and extends through Epsilon Tauri (ε Tau). Tomorrow, Mars is on that line.
- March 18: Over 50° in altitude in the west-southwest, Mars passes 4.0° to the upper right of ε Tau. Within the starfield, the planet is 0.8° to the upper right of Kappa Tauri (κ Tau) and 0.3° to the upper right of Upsilon Tauri (υ Tau).
- March 19: Over 50° up in the west-southwest, Mars is 3.2° to the lower right of the crescent moon that is over one-third illuminated.
- March 20: Over halfway up in the west-southwest, Mars passes 6.9° to the upper right of Aldebaran. This evening the planet is nearly 10° to the upper left of Alcyone. The moon appears to be caught between the Bull’s Horns.
- March 24: Mars – over halfway up in the west-southwest – is 0.7° to the upper right of Tau Tauri (τ Tau).
Mars marches through Taurus during the month. During evening hours, use a binocular to track its eastward trek compared to your favorite stars in the constellation.
Here’s more about Mars during 2021.
July 6, 2021: In less than a week, brilliant Venus passes Mars in the west-northwestern sky after sunset. This evening the two planets are 3.8° apart. Venus is over 18° to the lower right of the star Regulus.
July 1 – July 7, 2021, the waning crescent appears in the eastern sky. Early in the viewing period, the moon is among the dim stars of Pisces. As the week progresses, the moon wanes and moves farther eastward, appearing near Taurus.
July 5, 2021: Our planet Earth reaches its farthest point in its yearly trek around the sun. Our seasons are not related to Earth’s distance from the sun. Coincidentally, the moon is at its farthest point from Earth today.
July 5, 2021: Venus continues to close in on Mars in the west-northwest after sunset. In a week Venus passes the Red Planet.
July 4, 2021: The Venus – Mars conjunction is eight days away. This evening Venus moves to within 5° of the Red Planet.