Today we're going to talk about one of the most active meteor showers and one that's well worth seeing: the Geminids . This group of meteors appears to originate from a point in the constellation Gemini, hence its name, and is visible from early to mid-December. It reaches its peak around December 14th each year, when you can see 100 or more meteors per hour.
In this article we are going to tell you everything you need to know about the Geminids, their characteristics and how to see them.
Key features
Provided the sky conditions are ideal, with sufficient visibility and a moonless night, it's possible to see more than 100 meteors per hour during the peak of the Geminids . This makes it the most active meteor shower currently visible. It's on par with the Quadrantids, which occur in January.
In addition to intense radiation, the gravitational force exerted by the sun can also break through the outer layers of comets or asteroids. Remnants remain in orbit and move at extremely fast speeds, and when Earth gets close enough, they enter the atmosphere. The friction caused by contact with atmospheric gases ionizes them, appearing as a flash of light at high altitude, and the heat completely evaporates the meteor.
The fragments rarely fall to the ground. In this case, they are called meteorites, and when they are still in orbit, they are called meteoroids . In this way, debris is classified, depending on whether it is outside the atmosphere, inside the atmosphere, or eventually lands.
Origin of the Geminids
The Geminids are a rather unusual meteor shower because their origin is not a comet, but an asteroid. The asteroid is known as Phaethon and was discovered in 1983. Almost all meteor showers are formed by comets, making the Geminids the exception.
Astronomers disagree with the nature of this object because it appears to have a mixed asteroid-comet characteristic, although observations did not reveal the typical Phaeton coma of comets. The general difference between one celestial body and another is that comets are usually made of ice, while asteroids must be rocks.
There is a hypothesis that the Phaeton was a comet 2000 years ago, but when it was very close to the sun, its gravity caused a great disaster, the orbit changed tremendously, leaving behind a large amount of debris, today we call it Geminids.
It appears that the Gemini meteor showers did not appear immediately after this event, because the first record of their appearance dates back to 1862. On the other hand, other meteor showers, such as the Perseids and the Leonids themselves, have existed for centuries.
The fact is that even if the meteor shower is related to the debris left by asteroids and comets, it is not always possible to see the debris left by the last approach each year.
The debris that produced this year's meteor may have been created a long time ago and has remained in orbit ever since. But we must consider that the orbits are not stationary, they change due to gravitational interaction with other objects.
Description of the Geminids
The Geminids get their name because they appear to originate from a point in the constellation Gemini called the radiant. This is just an effect of perspective, because the paths are parallel and appear to converge in the distance, like train tracks. But it provides a naming convention for all major meteor showers, so these meteor showers are named after the constellation where the radiant is located.
The shower becomes visible around December 4th and continues until the 17th, with peak activity around the 13th or 14th. The Zenith Hourly Rate (ZHR) is the number of meteors per hour under ideal viewing conditions, including cloudless, moonless skies.
The zenith rate of the Geminid meteor shower is one of the highest: 100-120 meteors per hour , demonstrating that the fragments left behind by Phaethon have not dispersed much so far. Furthermore, observations show that the zenith rate has increased slightly since the shower was discovered.
The population index measures the brightness of the trails left by the meteor cluster, and the Gemini meteor shower is yellow. It depends on factors such as the mass and speed of the meteor, and is represented by r.
Its value is almost always set at 2 , but in a mathematical model adjusted to Gemini's behavior, the value is r = 2.4, which is 2.6 during the period of maximum activity. The yellow color alone indicates the possible presence of iron and sodium in the composition of the fragments.
When and how to observe them
To observe the Geminid meteor shower, you can go anywhere on the planet. They are visible from both hemispheres, although they are more clearly visible from the Northern Hemisphere. The radiant becomes visible in the evening, while in the Southern Hemisphere, you have to wait until midnight. As with any meteor shower, the rate of meteors per hour increases as time passes and the radiant rises higher in the sky. The best time to observe the Geminid meteor shower is during the early morning hours until sunrise.
The meteor shower will continue throughout the day, but it's more difficult to see because the meteors aren't as fast as in other showers. The best views are from a location far from city light pollution , on a moonless night, and at a good altitude. The number of meteors will increase as the night progresses.
I hope that with this information you can learn more about the Geminids and their characteristics.