Weekly Stargazing Highlights in the Northern Hemisphere: See Saturn and This Year's Last Supermoon

Each Monday, a new celestial is highlighted for the northern hemisphere. For instance, the full moon known as the "Harvest Moon" takes center stage in the night sky this week, earning the "supermoon" label.

While the term "supermoon" originates from astrology and sparks discussions among astronomers, it's a chance to admire its splendor as it rises in the early evening, reaching 100% full later in the week.

Watch Out for the Supermoon This Week!

In the southeastern night sky, a 91%-illuminated waxing gibbous moon appears, situated approximately 3 degrees below the captivating presence of Saturn. This celestial alignment offers an ideal opportunity for dusting off your telescope and indulging in some stargazing.

Beneath this pair of the moon and planet, one can observe a fairly luminous star known as Fomalhaut. It serves as the primary star in the Piscis Austrinus constellation, commonly known as the "Southern Fish." Remarkably, Fomalhaut is positioned at a mere 25 light years' distance from our Solar System.

Recent observations by the James Webb Space Telescope have uncovered compelling evidence of planets orbiting this intriguing star. In ancient times, Fomalhaut held the title of "Watcher of the South" and was considered one of the "Royal Stars," alongside Aldebaran in Taurus, Regulus in Leo, and Antares in Scorpius.

On Thursday, September 28, the northern hemisphere is in for a celestial treat known as the "Harvest Moon." While technically the moon reaches its full phase the following day, it is this particular evening when it graces the eastern horizon just after sunset, offering the best viewing opportunity.

This full moon is dubbed a "supermoon" because it coincides with the moon's closest approach to Earth, known as perigee, in its elliptical orbit.

To witness the "Harvest Supermoon" as it emerges on the eastern horizon, be prepared for a sight that may captivate stargazers with its orange hue. This distinct coloration is a result of Rayleigh scattering, a phenomenon where light is deflected by nitrogen and oxygen molecules in Earth's atmosphere.

While shorter-wavelength blue and green light gets scattered, longer-wavelength red and orange light tends to pass through the atmosphere more readily and reach your eyes.

The underlying physics that produces this mesmerizing lunar display is akin to what occurs during moonsets, sunrises, and sunsets, where the interplay of light and Earth's atmosphere creates awe-inspiring visual spectacles.

Supermoon Defined: Why Does the Moon Appear Bigger?

The term "Supermoon" is not an official astronomical classification but was coined by astrologer Richard Nolle in 1979. Nolle defined it as a New or Full Moon occurring when the Moon is at or near its closest approach to Earth in its orbit, with a 90% cut-off point that remains unclear in its origin.

There are no universally agreed-upon criteria for what qualifies as a Supermoon or Micro Moon, leading to different definitions among sources. It is simply defined as a Full or New Moon when the Moon's center is less than 360,000 kilometers (approximately 223,694 miles) from the center of Earth.

Conversely, a Micromoon occurs when the Moon's center is farther than 405,000 kilometers (about 251,655 miles) from Earth's center. A Super Full Moon appears 12.5% to 14.1% larger than a Micro Full Moon and 5.9% to 6.9% larger than an average Full Moon within the years 1550-2650.

Technically, it is referred to as "perigee-syzygy" in the Earth-Moon-Sun system, with "syzygy" denoting the straight-line configuration of three celestial bodies. When the Moon aligns closely with its lunar nodes during syzygy, it can lead to total solar or lunar eclipses. Supermoons appear about 16% brighter than average Full Moons because of their proximity to Earth.

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