Liberal Arts Blog — Triple Wonder: Venus, Mercury, and the Crescent Moon on Sunday, May 24th

Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day

Today’s Topic: Triple Wonder: Venus, Mercury, and the Crescent moon on the Evening of Sunday May 24th

Put it on your calendar. Just after sunset on Sunday May 24th, plan to go to a place where you can see a broad expanse of western sky. If you are not able to leave your home, just imagine it. This is the first in a series of monthly posts in which I will flag the astronomical highlight of the upcoming month. The night sky is the greatest show on earth. Don’t miss it. This post also includes a few amazing facts about Mercury and the two space probes (Mariner 10 and MESSENGER) sent to investigate it. Experts — please chime in. Correct, elaborate, elucidate.

THE PRELUDE — A falling Venus and a rising Mercury (May 4 — May 24)

1. On May 4th, the sun’s glare hides the appearance of Mercury in the western sky, but gradually Mercury climbs higher day by day until it becomes visible between the 11th and the 18th.

2. “Fortunately, we can use Venus to help us locate Mercury in May 2020. Throughout the month, Venus will be falling toward the sunset while Mercury will be climbing away.”

3. “On or near May 21, 2020, watch for these two worlds to be within one degree of one another on the sky’s dome. If you can see Venus with the eye alone, then aim binoculars at Venus to see Mercury sharing a single binocular field with Venus.”


1. Surprise! Rocky. Barren. Kind of looks like the moon. No clouds like Venus.

2. Rotates very slowly — a day on Mercury lasts as long as 60 earth days.

3. Without an atmosphere, temperature swings are extreme — from 800 degrees to — 300 degrees.

NB: “Since Mercury is close to the Sun, it is very difficult to send a spacecraft to explore the planet. The gravity from the sun is constantly pulling on the spacecraft causing the ship to need lots of fuel in order to stop or slow down at Mercury.”

TWO SPACE PROBES SENT TO CHECK IT OUT: “Mercury 10” (1975) and “MESSENGER” (2015)

1. Mariner 10 flew by Mercury 3X but each time it passed by the same side of the planet so only 40–40% of the planet could be mapped. Among many other things, the mission taught us that Mercury has a magnetic field.

2. Mariner 10 was the first spacecraft to use an “interplanetary slingshot maneuver” — “using Venus to bend its flight path to bring its perihelion down to the level of Mercury’s orbit.

3. MESSENGER was launched in 2004 and took 7 years to reach the planet (compared to 9 months to get to Mars) orbited Mercury roughly 4000 times before crashing into the planet in April 2015.

NB: MESSENGER gathered data on the planet’s chemistry, geology, and magnetic field. Discoveries included: very dark (half as reflective as the moon), has a tail (like a comet), is “shrinking like a raisin,” has an “iron heart” — 85% the size of the planet as a whole.

Mercury (planet)

Mariner 10

Gravity assist

7 Remarkable Lessons from Messenger’s Mission to Mercury


Please share the coolest thing you learned this week related to science, engineering, or technology.

Or, even better, the coolest or most important thing you learned in your life related to science and engineering.

This is your chance to make someone else’s day. Or to cement in your mind something that you might otherwise forget. Or to think more deeply about something dear to your heart. Continuity is key to depth of thought.



Passionate about education, thinking citizenship, art, and passing bits on of wisdom of a long lifetime.

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John Muresianu

Passionate about education, thinking citizenship, art, and passing bits on of wisdom of a long lifetime.