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He’s the reason it’s called Comet Leonard.

Leonard discovered the comet on Jan. 3, during his regular shift on Mount Lemmon with the Catalina Sky Survey, a NASA-funded, UA-run mission to find and track potentially hazardous near-Earth objects.

His was the first new comet discovered anywhere on Earth in 2021, and within a few days of spotting it, he learned that its orbit might bring it close enough to be “backyard visible.”

“That’s a rare thing,” Leonard said. “For me personally and professionally, it’s like hitting the cosmic jackpot.”

Starting Thursday and lasting through the weekend, Comet Leonard should appear at dusk low in the west to southwestern sky between the horizon and an unmistakably bright planet Venus.

“This will be the only week (when) we’ll have a chance for naked-eye viewing,” Leonard said.

Just don’t expect too much from the researcher’s namesake space snowball. It probably won’t look like much without the aid of a telescope or binoculars. If it is visible to the naked eye at all, it will likely show up as little more than a fuzzy star.

With some magnification, though, the comet’s tail should be visible, he said.

The comet has already come as close to us as it ever will, streaking past our planet on Sunday at a speed of 44 miles per second and with a comfortable cushion of more than 21 million miles — or roughly 88 times the distance between the Earth and moon.

Last weekend, when the comet still appeared in the morning sky, Leonard said he could just barely see it with his own eyes from the top of Mount Lemmon. “It was very, very incipient, but it was there,” he said.

There’s a chance it could grow brighter in the coming days, as sunlight shines through the ice and dust of the comet’s corona and tail in a process known as “forward scattering.”

Or it may continue to dim as it streaks away from us, Leonard said. That’s the thing about comets: Their behavior can be unpredictable.

“As a wise astronomer once said, ‘Comets are like cats — both have tails and both do precisely what they want,’” he said.

Comet Leonard originated where most comets do: in the Oort Cloud of icy objects that marks the most distant edge of the solar system.

It has been “on approach” to the sun for the past 40,000 years or so, with an orbit that suggests it circled past this way at least once before about 80,000 years ago.

It won’t be back this way again, Leonard said.

On Friday, it is expected to fly close enough to Venus to create possible meteor showers in the Venusian sky with dust from its tail. Then, early next year, it will slingshot around the sun and out of the solar system, never to return.

This was the first of four comets Leonard has discovered this year alone, bringing his career total to 13 and counting after six years with the Catalina Sky Survey.

The survey leads the world when it comes to cataloging new comets and asteroids. Roughly half of all known near-Earth objects were discovered by survey staff members working in the mountains above Tucson over the past 23 years.

Because of the international scientific rules governing such things, all 13 of Leonard’s comets automatically carry his name, followed by unique number sequences that spell out when they were first spotted.

Leonard said nearly every Comet Leonard he has found to date has been so obscure and so far away that it will never be widely seen from Earth or known to anyone outside of his narrow field of research.

Obviously, Leonard C/2021 A1 is the exception.

That’s why the man who discovered it decided to spend a few days out at Organ Pipe Cactus National Monument this week, camping with his wife, a telescope and a camera under some of the darkest skies they could find within a few hours’ drive of Tucson.

“We have to say hello and goodbye to Comet Leonard,” Leonard said.