The Celestial Sphere

By Matthew Johnson

As we leave move into May we have a lengthening of daylight. April began with 12 hours and 45 minutes of daylight, and May will end with 15 hours and 4 minutes of daylight. This is a gain of 2 hours and 19 minutes as the Earth in its orbit heads toward the longer days and shorter nights of summer.

For the astronomer, there are benefits and challenges throughout the year. Near the winter solstice of late December, the sun sets around 4:15 p.m., providing 15 hours of darkness for observing, a long and mosquito-free evening. The low temperatures of the winter months also provide an atmosphere with less moisture in the air (the moisture is often condensed out), so the skies are clearer and images of the stars and planets can be better defined than in the warmer months.

On the negative side, however, the intrepid astronomer often has to set up his scope with darkness quickly approaching. Additionally, the frigid temperatures can lead to numb fingertips and toes, so hand warmers are recommended. 

The cold also effects the telescope itself. When one takes a telescope from the 68-degree environment of a house into the 28-degree chill of a winter night, the optics of the telescope encounter a 40-degree difference. One must often have to wait 20 to 30 minutes for the glass in the lenses and mirrors of the telescope to come to thermal equilibrium. Otherwise images in the scope appear blurry. 

During the summer and early months of fall, on the other hand, one has to wait until after 8 p.m. for the sun to set before observing can begin, resulting in four hours less time to observe during summer than during the long nights of winter.  

The April 8, 2024, solar eclipse motivated large groups of enthusiasts to travel to locations where the sun’s light would be eclipsed by the moon. The more than 30 million Americans living in the wide “path of totality,” however, did not have to travel to experience the full solar eclipse, they just needed to look upward.

Total eclipses of the sun provide scientists with a unique solar and planetary geometry allowing the study of the physics of the sun’s chromosphere. When one thinks of a group of solar scientists who study the physics of the sun, the staff at NASA comes to mind, as it does with mostly all space projects.

I did a search for other groups of space scientists, looking for the more esoteric. One interesting group, based at the Institute for Astronomy in Honolulu, Hawaii, takes advantage of what an eclipse offers. They call themselves the Solar Wind Sherpas, “total eclipse chasers in search of the physics of the corona and the solar wind.” The Sherpas are a team of international scientists and explorers who travel the world to observe and collect data on total solar eclipses. 

The Sherpas website offers an excellent explanation of what the group does. At the end of this article—and all future ones—I will provide information on interesting websites. Bookmarking these sites will provide very good resources for amateur astronomers and scientists.

Planets 
At around 5 a.m. on May 1, Saturn can be viewed high in the eastern sky. If you have a flat horizon, Mercury can be viewed below Saturn, and if one has binoculars or a spotting scope, Mars can be seen as a small, dim orange/red dot halfway between Saturn and Mercury. 

On May 13, look toward the west about 90 minutes after the sun sets, toward the crescent moon. Just a slight distance away from the moon is an object in the constellation Cancer that is referred to as the Beehive Cluster. 

The Beehive Cluster, M44 (also known as Praesepe, Latin for “manger” or “crib”), is an open star cluster. It is one of the clusters nearest to Earth. Ptolemy, a classical astronomer, described it as a “nebulous mass in the center of Cancer.” Probably since it had been known and revered by astronomers since ancient times, Galileo also studied the cluster.  

This month Jupiter, which has graced our skies since the fall of 2023, will pass very close to the sun as its orbit now carries it around the far side of the solar system from the Earth. 

At its closest approach to the sun, Jupiter will be at a tiny separation from the sun, making it unobservable for a few weeks while it is lost in the sun’s glare. At this time, Jupiter will be at its most distant from Earth. It will be about six AU (an AU, or astronomical unit, is approximately 93 million miles).

Moon Phases
May 1: Last quarter (left half of the moon illuminated).
May 7: New moon (no visible moon). The best time of the month to observe faint objects such as distant galaxies and star clusters is during the few days before and after the new moon because there is no moonlight to interfere.
May 15: First quarter (right half of moon illuminated).
May 23: Full moon. 
May 30: Last quarter (left half of moon illuminated).
May’s full moon is known by Native American tribes as the “Flower Moon,” owing to the abundance of flowers in most regions. It was also referred to as the “Corn Planting Moon” and the “Milk Moon.”

Meteor Showers
The Eta Aquarids meteor shower peaks the night of May 4. The radiant, or where the meteors appear from in the sky, is in the direction of the constellation Aquarius. The Eta Aquarids are best viewed from the Southern Hemisphere, but they are easily viewed from the United States as well. The shower is caused by the Earth’s orbit intersecting with dust and debris from the passage of Halley’s Comet. These meteors are known for their high speed, estimated to be around 66 kilometers per second, or about 150,000 miles per hour. Since the moon will be close to the new moon phase, conditions for observing the meteors will be optimal. 

Comet
Comet 12/Pons-Brooks, discovered by Jean-Louis Pons on July 12, 1812, and independently rediscovered by William Brooks in 1883, was discussed at length in the March issue. The comet continues to impress astronomers and the public alike. For recent information on the comet’s behavior and location, refer to the website given below.                                                 

Websites
The Solar Wind Sherpas: https://project.ifa.hawaii.edu/solarwindsherpas.

Comet 12/Pons-Brooks: https://earthsky.org/tonight/12-p-comet-pons-brooks-outburst-millennium-falcon-bright-2024-eclipse/.