2021, April 10: Mars, Taurus, Crab Nebula

2021, April 10: Mars is halfway up in the west after sunset near the Bull’s horns.
2021, April 10: Mars is halfway up in the west after sunset near the Bull’s horns.

April 10, 2021: After sunset, Mars is about halfway up in the western sky near the horns of Taurus.  Mars is somewhat close to the Crab Nebula.  A telescope reveals a dim, cloudy patch of light.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:18 a.m. CDT; Sunset, 7:27 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Mars continues its eastward march in Taurus.  The planet is about halfway up in the west an hour after sunset.

The Red Planet is approaching the Bull’s horns, Elnath and Zeta Tauri (ζ Tau on the chart).  During the next few evenings watch the planet move between the two stars.

This evening, Mars is 3.9° to the lower left of Elnath and 4.4° to the lower right of Zeta Tauri.

If you have a telescope with moderate aperture, 4 inches to 6 inches or larger, and you live in a moderately dark location, you might locate the Crab Nebula, also known as Messier 1.

Imagine a line from Zeta Tauri to Mars.  Begin at the star and move the telescope about one-fourth of the way to Mars.  The nebula appears in the eyepiece.

This view of the Crab Nebula in visible light comes from the Hubble Space Telescope and spans 12 light-years. The supernova remnant, located 6,500 light-years away in the constellation Taurus, is among the best-studied objects in the sky. Credits: NASA/ESA/ASU/J. Hester
This view of the Crab Nebula in visible light comes from the Hubble Space Telescope and spans 12 light-years. The supernova remnant, located 6,500 light-years away in the constellation Taurus, is among the best-studied objects in the sky. Credits: NASA/ESA/ASU/J. Hester

Even through a telescope, the nebula appears as a smudge.  Time exposure photography collects light to provide the details of the tangles of gas.  The cloud is rushing outward from a rotating neutron star, the rapidly spinning mass of the stellar core. The rotating pulsar sends out a stream of light, like that of a lighthouse.  When the star turns earthward, we record a flash of radio waves.  When timing equipment is used, the pulsar can be seen flashing.

The nebula is the remnant of a supernova that appeared in the skies of Earth during the year 1054.  Chinese astronomers recorded the event.  The supernova was visible for two years before it faded from the view of the human eye.

The Crab Nebula represents the terminal state of the life cycle of a star.  It confirms stellar evolution theory, similar to the existence of stellar black holes and white dwarfs.

The nebula’s luminescence is from accelerating atomic particles through magnetic fields, like those produced in particle accelerators in scientific laboratories.

Astronomer Geoffrey Burbidge has noted the importance of the Crab Nebula by saying that there are two parts of astronomy – “the astronomy of the Crab Nebula and the astronomy of everything else.”

Here’s more about Mars during 2021.

Read about Mars during April.

Detailed Note: One hour before sunrise, Jupiter and Saturn are low in the southeastern sky.  Both are slowly trekking eastward in front of the stars of Capricornus.  Jupiter, over 10° up in the east-southeast, is 2.0° to the upper left of Deneb Algedi.  Saturn, 12.9° to the upper right of Jupiter, is over 15° in altitude in the southeast.  Among the stars, the Ringed Wonder is 2.0° to the upper right of θ Cap.  In the evening sky, about an hour after sunset, Mars is about halfway up in the west, marching eastward in Taurus near the horns of the Bull.  The Red Planet is 3.9° to the lower left of Elnath and 4.4° to the lower right of ζ Tau.

Read more about the planets during April 2021.

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