The "Devil Comet" 12P: Visibility Guide 2024

Astronomers and stargazers are currently tracking a rare celestial visitor that visits our inner solar system only once every 71 years. Comet 12P/Pons-Brooks, widely nicknamed the “Devil Comet” due to its distinctive horned appearance during outbursts, is making its approach this spring. This guide covers specific dates, viewing equipment, and exactly where to look to spot this cryovolcanic phenomenon.

Understanding the "Devil Comet" Phenomenon

Comet 12P/Pons-Brooks is not your average ball of ice and dust. It is a massive cryovolcanic comet, which essentially means it is an ice volcano flying through space. The nucleus of the comet is estimated to be approximately 10.5 miles (17 kilometers) wide. For comparison, that is roughly twice the size of Mount Everest.

The “Devil” nickname comes from a specific event observed in July 2023. As the comet heated up, internal pressure built until it exploded, blasting dust and gas into space. The debris cloud formed a horseshoe shape that resembled horns. While the horns have become less distinct in recent weeks as the coma (the gas cloud around the nucleus) has expanded, the comet remains a volatile and bright object for observers.

This comet is a Halley-type comet, meaning its orbital period is between 20 and 200 years. 12P completes a lap around the sun every 71 years. The last time it was visible from Earth was in 1954, and after this 2024 appearance, it will not return until 2095.

Critical Dates for Viewing in 2024

The visibility of 12P/Pons-Brooks changes rapidly as it moves through the solar system. Here are the specific dates and milestones you need to mark on your calendar to maximize your chances of seeing it.

March through Early April: The Prime Window

For observers in the Northern Hemisphere, late March through early April offers the best viewing conditions. During this period, the comet moves from the constellation Andromeda into Pisces and then Aries.

• brightness: As of mid-March, the comet is hovering around magnitude 5.5 to 6. This is on the edge of naked-eye visibility under perfect dark-sky conditions but is easily visible with binoculars.
• Direction: Look West-Northwest shortly after sunset. The comet will be low on the horizon.

April 8: The Total Solar Eclipse

A unique opportunity occurs on April 8, 2024, during the Total Solar Eclipse crossing North America. During the few minutes of totality (when the moon completely blocks the sun), the sky will darken enough to reveal stars and planets.

• Location: Jupiter will be visible to the upper left of the eclipsed sun. Comet 12P will be situated roughly between Jupiter and the Sun, though closer to Jupiter.
• Visibility Warning: While theoretically visible, the comet will likely require binoculars to spot during the eclipse unless it undergoes a major outburst immediately prior.

April 21: Perihelion

On this date, the comet reaches its closest point to the Sun (Perihelion), at a distance of about 72.5 million miles (116.8 million km).

• Maximum Brightness: This is when the comet is expected to be brightest, potentially reaching magnitude 4.5.
• Viewing Challenge: Despite being bright, it will be very close to the Sun from our perspective, making it difficult to see in the sun’s glare.

June 2: Closest Approach to Earth

The comet will be closest to Earth on June 2, passing at a safe distance of 144 million miles (232 million km). However, by this time, it will have moved into the southern sky, becoming largely invisible to viewers in North America and Europe while putting on a show for the Southern Hemisphere.

Recommended Gear and Apps

While headlines often suggest you can see this with the naked eye, relying on optical aids will significantly improve your experience. The “green fuzz” of a comet is notoriously harder to spot than a sharp star point of the same magnitude.

Binoculars are the Best Choice You do not need an expensive telescope. A standard pair of 10x50 binoculars is ideal. The “10” refers to magnification, and the “50” refers to the lens width in millimeters.

• Brands: Reliable options include the Nikon Aculon A211 or the Celestron Cometron 7x50, which are specifically designed with a wide field of view for tracking fast-moving objects.

Photography Gear If you plan to photograph the comet, a smartphone might struggle unless it has a dedicated astrophotography mode.

• DSLR/Mirrorless: Use a tripod and a lens with a fast aperture (f/2.8 or lower).
• Exposure: Try exposures between 10 to 20 seconds. Longer exposures without a star tracker will result in star trails.

Tracking Apps Since the comet moves slightly every night, star charts can become outdated quickly. Real-time apps are essential.

• Stellarium: A free open-source planetarium app that allows you to simulate the view from your specific location.
• The Sky Live: A website and app that provides live tracking coordinates (Right Ascension and Declination) for manual telescope users.

Why Does the Comet Look Green?

If you observe 12P/Pons-Brooks through a telescope or long-exposure photography, you will likely notice a distinct green hue. This is not a reflection of Earth’s atmosphere or a trick of the light.

The color comes from the comet’s chemical composition. As the sunlight heats the comet’s nucleus, it releases diatomic carbon (dicarbon). When dicarbon molecules are bombarded by sunlight in the vacuum of space, they break down and emit a green light. Interestingly, this green color usually stays contained within the coma (the head) of the comet and does not extend into the tail. The tail usually appears white or yellowish because it is made primarily of dust reflecting sunlight, or blue if it is an ion tail.

Frequently Asked Questions

Is Comet 12P/Pons-Brooks dangerous to Earth? No. The comet poses no threat to Earth. Even at its closest approach on June 2, 2024, it will be roughly 144 million miles away. That is more than 1.5 times the distance between the Earth and the Sun.

Can I see the comet from the city? Light pollution makes viewing comets very difficult. If you live in a major city, the comet will likely be washed out by streetlights. To see it, you should drive to a location with a Bortle Scale rating of 4 or lower (suburban to rural transition).

Why do they call it a “cryovolcano”? Unlike Earth volcanoes that spew molten rock (magma), cryovolcanoes on comets spew a mixture of water, ammonia, and methane ice. When the sun heats the comet, these frozen volatiles turn directly into gas (sublimation) and burst through the comet’s icy crust.

Will the “horns” come back? They might. The horned shape appears only after a significant outburst creates a shadow from the nucleus on the expanding gas cloud. Because 12P is highly volatile, another outburst could happen at any time as it gets closer to the sun, potentially restoring the “Devil” shape or causing a sudden spike in brightness.