Celestial fireworks to kick off the year
The year begins with the only major meteor shower in the first quarter of the year, with rates averaging about 40 meteors per hour under perfect conditions. However, the shower's peak this year is only a day past the last quarter Moon whose light will obscure all but the brightest meteors during the early morning hours, reducing the actual number observed. This shower is named after the obsolete constellation Quadrans Muralis the Wall Quadrant, and the old name stuck even after astronomers decided to replace the Wall Quadrant with a new constellation, Boӧtes the Herdsman ("bo-OH-teez"). The shower has a very narrow peak lasting only a few hours, but it's known for producing bright fireballs. This display is followed by something of a drought, with only weak meteor showers occurring until springtime.
Time to take a leap!
This year has 366 days instead of the usual 365. The addition of a 29th day to February is needed because the actual length of time it takes Earth to orbit the Sun is 365.25 days. Over four years, that extra quarter of a day adds up, and a correctional leap day is added to let the calendar catch up with the planet. The general rule that most remember is that leap day is added when the year is divisible by 4...but it's not quite that simple. To provide more precision over the long term, an additional rule has been added: end-of-century years cannot be leap years unless they're divisible by 400 (so 1700, 1800, and 1900 were not leap years, while) 2000 was). The next time a leap year will be skipped will be in 2100 (mark your calendars!).
Of lions, lambs, stars, and rams
Have you heard the expression "March comes in like a lion and goes out like a lamb"? Traditionally, it has been used in reference to the winter weather "roaring" like a lion in many areas at the beginning of the month. Then, things usually settle down and the month ends with the arrival of spring, usually bringing calmer, milder weather—lamb-like, or at least relatively so in comparison to the blustery storms that the month started with. There's also an astronomical context to the saying: In early March, the stars of the Zodiacal constellation Leo the Lion rise in the east during the early evening hours, and at the end of the month, those of Aries the Ram (not a lamb, but close enough) are setting in the west just after sunset.
Marching toward the equinox
- Spring in the northern hemisphere begins at 8:07 pm PT on March 19, 2024. This is the midpoint between the two solstices, and north of the equator this is known as the spring or vernal equinox. Because the seasons are reversed in the southern hemisphere, this date is the fall or autumnal equinox south of the equator. To avoid confusion, March 19 can also be referred to as the March equinox, which is appropriate in either hemisphere.
- On this date, Earth's axis of rotation is perpendicular to a line drawn from Earth to the Sun, and neither of the planet's poles is tipped more toward or away from the Sun than the other. Day and night everywhere are close to the same length—close, but not precisely the same. Due to atmospheric effects, a mirage of the Sun appears a few minutes before sunrise and lingers for a few minutes after sunset, so on the equinox, the time that some part of the Sun is visible above the horizon is longer by a few minutes than the period that it's entirely-hidden below it. The day when the Sun is visually above and below the horizon for equal lengths of time is known as the equilux, and the exact date varies with latitude. For 40°N, that happens two days before the equinox, on March 17.
- As seen from Earth, the Sun crosses the celestial equator, moving from the southern half of the celestial hemisphere into the northern half. This takes place against the stars of Pisces the Fishes.
April's total solar eclipse
Although this event occurs next season, it happens in early April, so we thought it would be prudent to cover it. Weather-permitting, observers lucky enough to be on the cross-country path of totality for the solar eclipse of April 8 will be able to see the Moon blot out the Sun's disk, revealing our star's faint outer atmosphere (or corona) for about four all-too-short minutes. During that time, the sky will briefly darken to a twilight level, allowing brighter objects that are usually seen at night to become visible—Jupiter will be about 30° to the northeast of the eclipsed Sun, and Venus will be on the other side, about 15° to the Sun's southwest. Although Mercury, Mars, and Saturn will also be in the sky, they're not expected to be bright enough to be easily observed. Observers in San Francisco will be too far from the path, missing totality, and will have to settle for a partial solar eclipse, with the Moon blocking less than half of the Sun's diameter (44%) from view.
A comet too?
At the time of this writing, yet another solar system object is causing some excitement, because it'll be in the sky during the eclipse, although how bright it will get is uncertain. Discovered in 1812, periodic comet 12P/Pons-Brooks is known for occasional outbursts causing as much as a hundredfold increase in brightness and will be closest to the Sun on April 21. This point (perihelion) is typically when a comet is most visible from Earth, but comet brightness is notoriously-difficult to predict. Pons-Brooks is not currently expected to become as bright as other Great Comets of the last century such as Hyakutake (1996), Hale-Bopp (1997), or—most recently—Neowise (2020), and you can learn more about it at https://www.astronomy.com/observing/a-comet-will-be-visible-during-the-2024-total-solar-eclipse…but beware the hype!
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