The month of April is named after the word “aprilis,” which is derived from the Latin aperire meaning “to open.” That is exactly what much of the northern hemisphere of the earth is starting to do during this first full month of spring. Our landscape will not really be transformed until next month, but it will start this month as many sure signs of spring will appear and the ice will melt completely out of our lakes and rivers.

Since the days are getting longer now and the nights are getting warmer, this will be a good month to get outside to view the beauty of the night sky and contemplate our place in it. As T.S. Eliot said “April is the cruelest month,” so we can’t just count on it getting continually warmer and greener this month. There will be many interesting highlights in the sky this month as spring begins to take hold of this hemisphere again and the whole earth will celebrate Earth Day on April 22, as we do every year.

The first full week of this month, April 5-12, is also International Dark Sky Week. Its purpose is to help raise the awareness to the importance of preserving our heritage of dark skies where they still exist and to help restore darker skies to more light-polluted places by advocating for more effective lighting. People around the globe can contribute as citizen scientists by going to the Globe at Night website to monitor the night sky where they live based on how many stars can be seen in certain constellations. This can be done for 10 days every month around the new moon, not just during the first week of April.

About 83% of the world’s population of 7.85 billion people live in light-polluted cities and towns and about half of those people have never experienced truly dark and pristine skies, where the Milky Way can be seen. We are lucky here in Maine that dark skies are close by, but much of the world has lost that resource and the best part is that we can do something about it quite easily. This is a good follow-up to the International Earth Hour on March 27 when millions of people and hundreds of cities turned off all non-essential lights for one hour.

The highlights that we can enjoy this month include a continuation of Mars ruling the night along with the long-awaited return of Venus to our evening sky late this month. As a bonus, Mercury will join Venus very low in the western sky right after sunset. Then Saturn rises about 4:30 a.m. followed by Jupiter half an hour later in Capricorn. The asteroid Vesta will be easy to see in Leo with a pair of binoculars and another comet named ATLAS will be visible in Hercules with a telescope. Then we have the first good meteor shower since the Quadrantids. That is the Lyrids on April 22.

Orange Mars can still be found in Taurus until April 24 when it transitions into Gemini. Notice that the red planet is moving in its direct eastward motion at the rate of one constellation per month, or about one degree per day. The net result is that it rises and sets about the same time each day, nearly matching our revolution around the sun. Compare its orange hue with the orange giant star Aldebaran in Taurus located 65 light years away and the deeper orange glow of the red super giant star Betelgeuse in Orion at 640 light years away. Mars continues to get a little fainter each night as we pull farther ahead of it in our orbits around the sun. Aldebaran is about twice as bright as Mars now as is Betelgeuse, which has returned from its dimmest appearance in recorded history early last year when it got as faint as 1.8 magnitude. It is about 0.8 magnitude now, similar to Aldebaran.

As you watch Mars move a little every evening against the background of stars, keep in mind the great success the Perseverance rover is enjoying on its surface as it continues its explorations. We are getting ready to fly the Ingenuity drone later this month or next month. This will be the first powered flight ever attempted by humans on another planet, and it will happen just 118 years after the Wright Brothers little flight on that beach in Kitty Hawk, North Carolina, and 52 years after we first walked on the moon. Since the Mars air is just one percent as dense as ours, it will be similar to flying 100,000 feet above the earth, which no helicopter has ever done before.

After Mars sets around midnight we have a long stretch of time with no planets visible. Then Saturn appears around 4:30 followed closely by Jupiter. The brightest asteroid, Vesta, will trace a nice loop in Leo this month. At a magnitude of 6.6, just fainter than the naked eye limit of 6.0, you can easily spot it in a pair of binoculars. It is our second largest asteroid with a diameter of 310 miles, or about the size of Arizona. Ceres is the biggest at 600 miles across. Just these two asteroids make up about half the mass of all the one million plus identified asteroids in the belt between Mars and Jupiter.

Just recently discovered with the two ATLAS telescopes in Hawaii, located about 100 miles apart, Comet C/2020 R4 (ATLAS) should reach about 11th magnitude this month in Hercules and Bootes. So you would need a good amateur telescope to see it. ATLAS is an acronym for the ominous-sounding set of words, Asteroid Impact Last Alert System. ATLAS has already found 575 near-earth asteroids, 60 potentially hazardous asteroids that are on an orbit that crosses ours around the sun, 58 comets, and even 8,327 supernovae in other galaxies.

The Lyrid Meteor Shower will peak on April 22. Caused by Comet Thatcher, you can expect up to 18 meteors per hour from a dark-sky site. The waxing gibbous moon will not set until about 4 a.m., so you will have a short window to see these meteors just before sunrise, which is usually the best time to see them anyway because the earth is rotating into the meteors after midnight. They will all emanate from the constellation of Lyra, which is part of the Summer Triangle and doesn’t rise until later in the morning.

APRIL HIGHLIGHTS

April 1: In 1997, Comet Hale-Bopp made its closest approach to the sun. This was a once-in-a-lifetime comet that took over half the sky in March and April of that year. I remember seeing and photographing it many times. It was preceded by another once-in-a-lifetime comet just one year earlier, Comet Hyakutake, discovered by a Japanese photographer.

April 4: Last quarter moon is at 6:02 a.m.  Asteroid Metis is at opposition.

April 6: The moon passes 4 degrees south of Saturn this morning.

April 11: New moon is at 10:31 p.m. On this day in 1986 Halley’s Comet made its closest approach to Earth. I remember seeing this comet several times starting on Nov. 8, 1985.

April 12: In 1961, Yuri Gagarin became the first human to ever orbit the earth. John Glenn accomplished that feat less than a year later on Feb. 20, 1962.

April 17: The moon passes less than one degree south of Mars this evening.

April 18: Mercury is in superior conjunction with the sun today.

April 20: First quarter moon is at 2:59 a.m.

April 22: The Lyrid Meteor shower peaks this morning.

April 25: The Hubble Space Telescope was deployed in 1990 with the Space Shuttle Discovery, STS-31. It is still up there and functioning 31 years and millions of great pictures and discoveries later.

April 26: Full moon is at 11:32 p.m. This will also be the first super moon of the year since it will occur just 12 hours before perigee, or its closest approach to Earth for the month.

April 30: Frances Wright, an American astronomer who taught celestial navigation at Harvard to Naval officers and wrote 3 books on celestial navigation, was born in 1897.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.