Bob Moler's Ephemeris Blog

This is Bob Moler with Ephemeris for Tuesday, April 25th. Today the Sun will be up for 13 hours and 57 minutes, setting at 8:40, and it will rise tomorrow at 6:40. The Moon, 2 days before first quarter, will set at 2:50 tomorrow morning.

Tonight, the Moon and the planet Mars will appear close to each other. The Red Planet will appear just below and left of the waxing crescent Moon. Mars is a lot dimmer than it was last December. That’s because it is a lot farther away than it was back then, 157 versus 51 million miles (253 versus 82 million kilometers). Mars is the planet with the greatest distance variation percentage over its synodic period, that is, from opposition to the next opposition. It also has the longest synodic period, at 26 months on average. That’s why opportunities to launch spacecraft only occur every 26 months. The least energy it takes to get to Mars occurs when a spacecraft is launched a few months before opposition, when Mars is at its closest, to arrive several months after opposition.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –4 hours). They may be different for your location.

Addendum

The Moon and Mars as they should appear in the west tonight, April 25, 2023, at 10 pm. Created using Stellarium.

Illustration of the route Mars 2020 (Perseverance) took to arrive at the Red Planet, including several trajectory correction maneuvers (TCMs) to adjust its flight path. Credit NASA/JPL.