Earth may have another moon ... sort of

Earth is the only planet in our solar system with a single moon, making it a rare phenomenon for a planet of its kind. While many other objects in the solar system have single moons, including some dwarf planets and asteroids, the large gas and ice giants like Jupiter and Saturn have dozens of moons, and inner planets like Venus and Mercury have none. The formation of Earth's Moon theorized through a giant impact is considered a rare event.

However, our planet’s gravity has captured asteroids or comets that orbit Earth for a short time before returning to their usual orbit around the sun. These are referred to as “mini-moons,” or quasi-moons. Recently, astronomers spotted one of these small space rocks orbiting our planet. This object is so small that it went unseen by telescopes for approximately 60 years. According to a paper in the journal called “Research Notes of the American Astronomical Society, the newly discovered object is called 2025 PN7 and is around 238,000 miles from Earth on average. Scientists estimate that this small object is likely to hang around Earth for another 60 years before the sun’s gravity pulls it back.

In February 2020, it was discovered that our planet had another “mini-moon.” The small space rock, which was about 3 feet wide, was orbiting Earth for about a year before flying back out into space. In 2006, there was another confirmed mini-moon orbiting our planet.

The planet in our Solar System that has the most moons is Saturn. Saturn has a total of 274 confirmed moons. In fact, early this year, space scientists discovered 128 more moons orbiting Saturn, bringing the total to 274.

For the longest time, it was believed that Jupiter had the greatest number of moons. With better technology and astronomical tools and methods, it was recently confirmed that the number of moons surrounding Jupiter had risen to 95 as of early 2025. Previous estimates had the number of Jovian moons in the 70s. However, Jupiter may one day recapture the No. 1 spot of having the most moons. A recent study from the Department of Physics and Astronomy at the University of British Columbia estimates that Jupiter may have as many as 600 irregular moons.

The 600 Jovian moons are an estimate based on archival 2010 data from the Canada-France-Hawaii Telescope. Researchers looked at a small area and found nearly 50 small, irregular moons. Based on that observation, they computed the number of small moons that are likely orbiting Jupiter, which comes to 600. By the way, Uranus has 29 confirmed moons, while Neptune has 16 known moons. The so-called dwarf planet Pluto has five natural satellites.

As I’ve mentioned in previous columns, many of our long-range forecasts are based upon the lunar cycles. Prior to the technological advances, farmers were planting by the moon for thousands of years. During the full moon and new moon cycles, upper-level winds will sometimes change as the low-pressure troughs, or dips in the jet stream, become greater, which usually brings bigger storms in the mid-latitudes. By contrast, high-pressure ridges will amplify, bringing dry weather. During the first and last quarter lunar phases, the jet stream often becomes more zonal and storm systems are usually not as intense.

Our moon is also drifting away from our planet at about 1.5 inches per year. So, if we’re here in 50 billion years, the moon will be far enough from our planet to take about 47 days to orbit the Earth, rather than the current 27.3 days. Ancient sedimentary rock and fossil shells suggest that about 600 million years ago, a day on Earth was about 21 hours as the moon was slightly closer. Currently, the moon’s distance from Earth is nearly 239,000 miles and is estimated to be about 150 miles closer than it was 600 million years ago.

In terms of our local weather, the Spokane and Coeur d’Alene region finally received some much-needed rainfall last week. Cliff’s station only picked up 0.07 inches, taking the September total to 0.09 inches. Many of the outlying regions received around a quarter to a third of an inch of moisture from last week’s storm. The Spokane International Airport has a total of 0.42 inches for the month.

Not much moisture is expected in our region through the end of the month. Therefore, September’s precipitation will end up below normal for the seventh month in a row.

There is a decent chance that conditions will start reversing toward the wetter side in the coming months. Forecasters are still predicting a better than 50/50 chance of a new cooler La Niña sea-surface temperature event being declared between October and December, which would likely lead to an increase in rain and snow in the coming months. However, this new La Niña is expected to be relatively weak and brief. New forecast models are indicating that sea-surface temperatures are expected to return to “neutral,” or as we call it, a “La Nada” in early 2026. Stay tuned.

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Contact Randy Mann at [email protected].