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Ephemeris: 04/21/2025 – Follow the spike to Spica

April 21, 2025

This is Ephemeris for Monday, April 21st. Today the Sun will be up for 13 hours and 47 minutes, setting at 8:35, and it will rise tomorrow at 6:46. The Moon, 1 day past last quarter, will rise at 4:25 tomorrow morning.

In the south-southeast at 10:30 p.m. is the bright star Spica, which can be found from all the way back overhead to the Big Dipper. Follow the arc of the handle of the Big Dipper to the bright star Arcturus below it in the east-southeast. Then straighten the curve of the arc to a straight spike which points to Spica, the brightest star in Virgo the virgin. Arcturus is much brighter than Spica and has an orange tint to Spica’s bluish hue. In fact, Spica is the bluest of the 21 first magnitude stars. That means that it has a really hot surface temperature. Actually, Spica is really two blue-white stars orbiting each other in 4 days. Spica is 250 light years away. It also was an important star to the ancient Greeks. One temple was built and aligned to its setting point. The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.

Addendum

How to find Spica from the Big Dipper
How to find Spica from the Big Dipper for 10 PM, second half of April. Created using My LookingUp app, LibreOffice Draw, and GIMP.
The binary stars that make up Spica in this artist's depiction
The binary stars that make up Spica in this artist’s depiction. The stars cannot be separated in telescopes, but were detected by their Doppler signatures in the stars’ spectra as they orbited each other.
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