April highlights include a major solar eclipse; a comet visible through binoculars; beautiful gatherings of the moon, planets and stars; two close planet pairs; and the annual large gathering of bright stars in the western sky at dusk.
On the first days of April, as darkness falls, note bright Jupiter in west, and the second-magnitude star Hamal, brightest star of Aries, within 14° to the planet’s lower right. Using binoculars, look for a fuzzy spot, perhaps of fifth magnitude, in the same field as Hamal. It’s comet 12P/Pons-Brooks, in its return to the inner solar system after nearly 71 years. Comet P-B is shifting position by 1.2° each day in relation to the starry background. Look to the star’s upper left, in the same binocular field, April 1-3.
Also near Jupiter and in the same binocular field is the 5.8-magnitude planet Uranus. Look above and slightly left of Jupiter, by 3° on April 3. On April 9, Uranus will be only 2° directly above Jupiter, and on April 15, just 1° to Jupiter’s upper right. Uranus will appear only 0.5° north (to the upper right) of Jupiter on April 20, but by then, the pair will be only 1° above the horizon at the end of evening twilight.
A bit less than an hour before sunrise, we can follow the planets Mars and Saturn, low, just south of east all month. We’ll also catch the waning moon during April’s first week, and again after the full moon of April 23. On April 1, the 57% moon appears in the Teapot of Sagittarius. This southernmost moon reaches its high point directly south only 27° up four minutes before sunrise as seen from the Coachella Valley. That’s 6° lower than the lowest midday sun of the year on the first day of winter, Dec. 21. During April 1-10, Mars and Saturn appear closer together each morning. On April 3, they’re 5° apart and easily fit within the same binocular field, while the 35% crescent moon stands in the southeast. On April 5, Mars is within 10° to the lower left of the 15% moon, while Saturn appears 3.6° to Mars’ lower left. On April 6, in brighter twilight, the very low moon (7%) forms a compact gathering with Saturn and Mars. The planets that morning are 3° apart, within 3° and 6° to the moon’s upper right. From lower left to upper right that morning, the gathering of the moon, Saturn and Mars will fit within a 6° field.
Mars and Saturn will nearly match in brightnessover the next few months, near first magnitude. Mars is slowly brightening, until a peak near its closest approach to Earth in January 2025. Saturn will fade at first, as its rings change from 4° from edgewise on April 9, to 1.9° at a temporary minimum in late June. Compare the color and brightness of these planets, especially around the date of their close conjunction on April 10,when they’re 0.5° apart. By the end of April, Saturn will appear 13° to the upper right of Mars. Mercury will be just then emerging, 17ˆ to Mars’ lower left.
The major solar eclipse: It will be seen on Monday, April 8, as total from within a track crossing Mexico, the United States from Texas to Maine, and eastern Canada. The event will be seen only as a partial solar eclipse from nearly all of the rest of North America, including here.
To avoid serious and possibly permanent harm, anyone who wishes to directly view the partial eclipse must use a viewing device that meets safety standards to greatly reduce the sun’s brightness, in visible light as well as invisible infrared and ultraviolet radiation. For descriptions of the standards, the viewing devices, and a list of reliable vendors, visit eclipse.aas.org/eye-safety. Without such a device, you can observe the eclipse indirectly, by projecting images using a colander or pinholes, or standing under a tree looking at projected images on the ground or the side of a building.
From the Coachella Valley, the first contact of the moon’s disk with the sun’s occurs at 10:06 a.m., as the moon begins to cover the right side of the sun. If the solar disk is imagined as the face of a clock, and viewed through a safe solar filter, then a tiny part of the moon’s silhouette will first be seen halfway between the 3 o’clock (right edge) and 4 o’clock positions. The coverage increases until maximum eclipse at 11:14 a.m., when the lower 61 percent of the sun’s diameter and 53 percent of the disk area are covered. The fraction of the sun hidden will then decrease until last contact, around 12:26 p.m., when the last tiny bit of the moon departs from the sun’s disk just above the 9 o’clock (left) edge of the imagined solar clock face.
Although there’ll be a total solar eclipse somewhere on Earth in 2026, 2027 and-2028, the next total solar eclipses in parts of U.S. will occur in March 2033 (northwest Alaska); August 2044 (North Dakota and Montana at sunset); and August 2045 (within a path from northern California to Florida). Those will all appear as partial eclipses in the Coachella Valley. Preceding those, we’ll have partial solar eclipses in the Coachella Valley on Jan. 29, 2029, and on Nov. 14, 2031.
At sunset on the evening on April 8, eclipse day, the moon will still be within 4° of the sun and not visible. At mid-twilight on the next evening, April 9, about 40 minutes after sunset, the moon’s age will be an easy 32 to 33 hours, well-placed 18 degrees from the sun. Look for the beautiful 3 percent crescent that evening, 11° to the lower right of Jupiter. It announces the beginning of the month of Shawwal in the Islamic calendar, and the end of the daytime fasting of Ramadan.
Comet 12P/Pons-Brooks, perhaps near its peak at magnitude of 4.5, appears through binoculars within 6° to the upper left of moon on April 9. As dusk deepens on April 10, the 8 percent moon appears 5° to the upper right of Jupiter, and 7° below the Pleiades star cluster. Later that night, the comet passes the descending node of its orbit, crossing southward through Earth’s orbital plane. On April 11, the moon is 7° above the Pleiades and within 10° to the right of Aldebaran and the Hyades cluster. On the 12th, the moon will appear very close to Elnath, the tip of the northern horn of Taurus, the Bull. On the 13th, about 1 3/4 hours before sunset, this month’s northernmost moon passes only 5° south of overhead, as seen from the Coachella Valley. That’s 5° higher than the highest sun of the year, at midday on June 20.
As darkness falls on April 13, the moon will be near the feet of Gemini, and the comet will be just 3° below Jupiter. On the nights of April 14 and 15, the moon skips past Castor and Pollux, and the bright stars of Gemini, and on the nights of April 17 and 18, the moon leapfrogs over Regulus, heart of Leo, the Lion. On the evening of April 20, the comet passes perihelion, 72.6 million miles from sun, but will be setting around the end of twilight. On the 22nd at dusk, the nearly full moon appears very close to Spica. Use binoculars to spot the star just south of the moon. At dusk on the 23rd, the full moon appears 13° to the lower left of Spica.
A week before the end of April, all the bright stars of winter are still easily visible in the western sky—but they’re poised to pull their annual disappearing act in the next several weeks. Follow the departures, in order, of Jupiter, Rigel, the Pleiades, Aldebaran, Sirius and Betelgeuse from the western sky. The spring stars, Arcturus and Spica, rise higher in the eastern sky during April. Watch for Vega, the vanguard of summer stars, rising in the far northeast.
To follow the moon until the end of the lunar month, which began with the solar eclipse, we shift our viewing time back to dawn, and we see the waning gibbous moon 5° west of Antares, heart of the Scorpion, on Apr. 26. We also see the summer triangle of Vega, Altair and Deneb approaching overhead these mornings, with Arcturus in the west, and Spica setting in west-southwest. Two mornings later, on the 28th, we have another southernmost moon, this time near the tip of the spout of the Teapot of Sagittarius. The moon reaches its high point in the south 1.6 hours before sunrise in the Coachella Valley that morning, again only 27° up, or 6° lower than the winter solstice midday sun.
The Astronomical Society of the Desert will host a star party on Saturday, April 13, at the Santa Rosa and San Jacinto Mountains National Monument Visitor Center; and on Saturday, April 27, at Sawmill Trailhead, a site in the Santa Rosa Mountains at elevation 4,000 feet. For dates and times of other star parties, and maps and directions to the two sites, visit astrorx.org.
The Abrams Planetarium Sky Calendaris available by subscription from www.abramsplanetarium.org/skycalendar. Links to free downloadable PDFs of the April 2024 Sky Calendar and evening skies constellation map are also available there. For $12 per year, subscribers receive quarterly mailings, each containing three monthly issues.
Robert Victor originated the Abrams Planetarium monthly Sky Calendar in October 1968 and still helps produce an occasional issue. He enjoys being outdoors sharing the beauty of the night sky and other wonders of nature. Robert Miller, who provided the evening and morning twilight charts, did graduate work in planetarium science, and later astronomy and computer science at Michigan State University, and remains active in research and public outreach in astronomy.
