June 2021
The Backyard Astronomer
by
Adam England

Mars, Cancer, and the Beehive Cluster

For the past couple of months the scientific community has been intently focused on Mars. 

M44 by Stuart Heggie, NASA-JPL

Every 26 months our planets align in a way that shortens travel time from Earth to Mars to about nine months, and as more countries develop space programs, more robotic explorers are sent to the red planet during this window. In 2021 the UAE orbiter Hope arrived on February 9, China’s Tianwen-1 entered orbit on February 10, and the NASA Perseverance rover touched down on February 18. 

Perseverance carried with it the Ingenuity helicopter, which has spent the last month proving the first powered flight on another world, and on May 14 Tianwen-1 released the Zhurong rover, making China only the second country to successfully land a rover on the Martian surface.

Mars by Joel Cohen


Mars is easily identifiable with the naked eye, its deep red hue due to high levels of oxidized iron in its crust. Basically the whole planet has rusted over the last couple billion years.

The arrivals of the orbiters and landers in February signaled a (relatively) close approach of our two planets. For most of 2021 they have been moving farther from one another, making Mars lower and dimmer in our night sky.

Sinking closer to the setting sun, Mars enters the constellation Cancer on June 8. As the month wanes, you may be able to catch one last conjunction with Mars passing just 0.5 arc-minutes from the Beehive Cluster M44 on June 23, just minutes after sunset, low in the western sky.

The Beehive Cluster – Messier 44 – is one of the nearest open clusters to Earth. Ptolemy referred to it as the “nebulous mass in the breast of Cancer,” proving how easily identifiable it is with the naked eye. Galileo resolved 40 stars within the cluster, though we now count at least 1,000 stars spread across 39 light-years, close enough to be gravitationally bound with one another. At least three exoplanets are known to orbit stars within the Beehive Cluster.

If you are lucky enough to catch the conjunction of this open cluster and our neighboring planet, both should easily fit within the field of view of your telescope or binoculars. With the right magnification, one can resolve some nebulosity from the Beehive Cluster and the Martian polar ice cap.

If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.

Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.