Take This Once-in-a-Lifetime Quiz on Rare Events

A comet is a small body of ice, gas, and rock particles orbiting the sun. When it gets close enough, its ice content sublimates and mixes with dust to form a brightly colored atmosphere around the comet, known as the tail. In September 1865, the Ikeya-Seki comet passed just 290,000 miles from the sun’s visible surface, allowing it to be seen clearly by the naked eye during the day.

The Chinchaga fire burned about 3.5 million acres of the boreal forest in Canada, causing one of the biggest atmospheric layers of smoke in history above the Northern Hemisphere, and giving the sun a bluish hue. The fire’s notable power and length — it burned from June through October — led to fire response and prevention policy changes by the government of Alberta.

The whitish-gray spots that sometimes appear on Saturn in photographs are actually intense systems of lightning and cloud movement. Unlike Jupiter’s Great Red Spot, the spots on Saturn are intermittent depending on the intensity of the storms. Scientists are still unsure why they happen, though some have theorized it relates to the density of water in Saturn’s hydrogen- and helium-heavy atmosphere.

During a total lunar eclipse, the Earth is between the sun and the moon, putting the moon in the darkest part of the Earth’s shadow, the umbra. Because very little light reaches the moon during a lunar eclipse, it appears to have a reddish-brown hue from Earth. Like solar eclipses, a blood moon occurs every one to two years.

Saturn and Jupiter are the two biggest planets in the solar system, And because of their orbits, you can see the two planets together in the sky roughly once every 20 years — a stunning visual treat that’s sometimes called a “Christmas star.” Despite appearing a fingernail’s length away from one another in the sky from Earth, Jupiter and Saturn are over 400 million miles apart.

September 9 is the most common birthday, followed by four other dates in September. So, what's with all these Virgos? Well, many of them were conceived on or around December 25. But while a lot of baby-making may happen on holidays, they’re not common times for births to occur. Aside from leap day, December 25 is the least common birthday, followed by January 1, December 24, and July 4, because many parents try to avoid scheduling births on holidays.

Also called the Superstorm of 1993, the Storm of the Century began as a cyclone that hit the Florida panhandle just after midnight on March 13. As it traveled up the coast and collided with cold air and strong winds, blizzard conditions developed, bringing record-setting precipitation and freezing temperatures to many places not used to heavy snow. Birmingham, Alabama, got 17 inches, while Asheville, North Carolina, saw over a foot and a half.

An eclipse occurs when one celestial body moves directly in between two others. During a total solar eclipse, the moon completely blocks the sun, casting a dark shadow on Earth that can make it seem like night during the day. This occurs somewhere on Earth once every 18 months, but from any one location, you can only see one total solar eclipse about every 400 years.

The 1815 eruption of Mount Tambora in Indonesia was one of the largest ever recorded, spewing about 31 million cubic miles of ash into the atmosphere. The eruption lasted five days in April, but caused a massive cloud of ash to orbit the Northern Hemisphere for the rest of the year, dropping the average global temperature by 1 degree Fahrenheit, and causing climate abnormalities felt around the world.

Typhoon Tip began gathering strength in the western Pacific Ocean in early October 1979, before making landfall in southern Japan later that month. During its formation, the U.S. Air Force sent 40 separate reconnaissance missions to better understand the storm. Of particular note was Tip’s diameter, 1,380 miles. If placed over the United States, the storm would have stretched from Dallas to New York City.

All of the eight planets in the solar system have different orbits: Mercury travels around the sun in 88 days, while Saturn takes the equivalent of 29 years to complete one orbit. Because of this discrepancy, it’s only every one to two years that even five planets can be seen at once, known as a cosmic parade. (And Uranus and Neptune, the two planets farthest from Earth, may require binoculars or a telescope to see clearly.)

Leap year compensates for the slight difference between a calendar year (365 days) and the actual time it takes the Earth to orbit the sun (about 365.24 days). In 46 BCE, with guidance from Roman astronomers, Julius Caesar adopted a calendar that added an extra day to the second month every four years. In 1582, Pope Gregory XIII tweaked the calendar so there would only be a leap day added to years divisible by four.

A “transit” is a phenomenon in which a celestial body moves directly between the observer and a larger body — in this case, the sun. The transit of Venus is a rare sight: Prior to the last transit in 2012, it hadn’t occurred since 1882. During the 1761 transit, the fuzzy halo visible above the planet led astronomers of the era to speculate that Venus had an atmosphere, a theory later proved by modern science.

The term “blue moon” dates to the early 20th-century agricultural industry, when farmer’s almanacs described it as an extra moon in a three-month season. Since there’s roughly one full moon in every month, the phrase is now more widely accepted to mean a second full moon in a month. It’s also an expression to describe something that happens rarely — a blue moon occurs roughly once every 33 months.

The English astronomer Edmond Halley didn’t actually discover his namesake comet, but he calculated its trajectory using theories created by Isaac Newton. The icy ball of dust and rock had been seen from Earth in 1531, 1607, and 1682. In 1705, Halley predicted the comet would next appear around the end of 1758 or the beginning of 1759. The next sighting was in December 1758, proving his theory right.