National Astronomical Observatory of Japan

Geminid Meteor Shower Peaks (December, 2018)

Geminid Meteor Shower and Mt. Fuji.
Medium resolution (2000 x 1265) Maximum resolution (4297 x 3045)

Let’s Watch the Geminid Meteor Shower under Good Conditions!

The peak (Note 1) of the 2018 Geminid meteor shower is expected to occur around 9 p.m. on December 14, Japan Standard Time. This year, the first quarter moon sets around midnight on December 15. After that, you can observe meteors under very good conditions.

It is thought that the meteor shower will be most active particularly on the two nights of the 13th and the 14th. Meteors begin to appear from about 8 p.m., and the meteor shower will be visible until the morning on both days.

It is predicted that you can observe up to about 40 per hour when you observe around the peak time under a dark night sky.

Shooting stars don’t appear in a set direction. So let’s observe a large area of the sky without thinking about which way to look. After going outside, your eyes need to adjust to the darkness, so please observe for at least 15 minutes. It is best to prepare a picnic blanket so that you can observe while lying down. It will be in the night time, so please be careful to avoid accidents. It is a very cold season, so please take proper precautions against the cold when observing.

(Note 1) The “peak” of meteor shower activity indicates the maximum activity of the meteoric shower itself and this period, without considering the observing places, time, or the conditions of the Moon. Back

About the Geminid Meteor Shower

The Geminid meteor shower is a meteor shower which is active around December 14 each year.

One characteristic is that many meteors are almost guaranteed to appear every year. It is known as one of “The 3 Major Meteor Showers,” along with the Quadrantids in January and the Perseids in August because many meteors appear every year. When you observe around the peak time under a dark night sky, you might observe over 40 per hour.

Another characteristic of the Geminids is that they appear before midnight and are visible throughout the night. Among the 3 Major Meteor Showers, the Perseids and the Quadrantids appear mainly from midnight to dawn. However, the Geminids mainly start to appear from an early time, around 8 p.m. This meteor shower is easy to observe for many people, especially children.

Therefore, the Geminids are ideal for people who want to observe their first meteor shower.

To Observe the Geminid Meteor Shower

Here we have collected information which could be useful for observing this year’s Geminid meteor shower.

The Appropriate Time for Observations

The Appropriate Date for Observations

It’s predicted that the most meteors will be visible starting from the night of December 13 until dawn on December 14 and the night of December 14 to dawn on December 15.

The peak of the Geminids is predicted to occur around 9 p.m. on December 14, Japan Standard Time. Therefore, it is expected the most meteors will be visible starting from the night of December 13 until dawn on December 14 and the night of December 14 to dawn on December 15.

However, we don’t know when the weather will be clear. It is also possible for meteoric activity to occur at times other than the predicted time. Regardless of the above predictions, please observe for as long as possible, as many nights as possible. This is the only way to improve your chances of seeing meteors.

The total active period of the Geminids is thought to last even longer, extending from around December 4 to December 17. As we move away from the day of the peak, the number of meteors which will appear decreases.

Time Period Suited for Observations

It would be best to observe between 10 p.m. and dawn as much as possible.

When the meteoric activity is constant, the higher the elevation of the radiant point (Note 2), the more meteors will appear.

For the Geminids, meteors will begin to appear from around 8 p.m. Continue observing for a while and you can see some meteors. However, since the radiant point is still not so high around this time, it is not the full shower. From about 10 p.m., many meteors begin to appear, and it is thought that the meteor shower will be visible until the morning.

The radiant point reaches its highest elevation around 2 a.m.

(Note 2) “Radiant point” is the point the meteors of the meteor shower seem to appear radially around. Back

The Effects of the Moonlight

Moonlight should not be a problem.

This year, December 15 is the first quarter moon.

For several days around the 14th when the most meteors will appear, the Moon sets around midnight.

When the Moon is still out, we cannot see the faint meteors due to the moonlight. But after the moon sets, we can observe the meteors in good conditions with no influence from the moonlight.

You can look up the times when the Moon rises and sets in the “Koyomi Station” of the NAOJ Ephemeris Computation Office.

Number of Meteors Which Can Be Seen

If you observe from a location with a sufficiently dark sky at the time with the most meteors, it should be possible to see around 40 per hour.

Here we assume that you are observing from a location with a sufficiently dark sky (i.e. 5.5 magnitude stars are visible with the naked eye when there is no moonlight.)

If you observe under town lights or at times other than the peak, the number of meteors which can be seen will be reduced to a fraction of this amount. On the other hand, people with sharp eyesight or veteran meteor observers might be able to catch twice as many.

Directions Suited for Observation and How to Distinguish Meteors Belonging to the Geminids

Radiant point of Geminid meteor shower
Medium resolution (2000 x 1265) High resolution (5500 x 3480)

It doesn’t matter which direction you look. Please watch a large area of the sky.

Meteors appear to radiate around the central point of the meteor shower. This central point is called the “radiant point.” For the Geminid meteor shower, the radiant point is near the second magnitude star Castor, which is one of the two bright stars in the constellation Gemini.

This is not to say that meteors appear only around the constellation Gemini where the radiant point is located. Meteors can appear anywhere in the night sky. For example, even if you look in the opposite direction from the radiant point, on average you can see as many meteors as if you watched in the direction of the radiant point.

So, you should concentrate on a wide area of the sky without worrying about the radiant point. The wider the area of sky you watch, the more likely you are to see many meteors.

During the period when the Geminid meteor shower is active, meteors other than the Geminids might also appear.

To determine whether it is one of the Geminids or not, please follow the meteor trail backwards and see if it passes through the radiant point of the Geminids. If it doesn’t point back towards the radiant point, it isn’t one of the Geminids; if it does, it is highly probable that it is one of the Geminids.

The length of the meteor trails changes based on their relative position to the radiant point. Because meteors which appear near the radiant point are flying towards us, most of them have short trails. In contrast, in directions removed from the radiant point, we see meteor trails from the side, so most of them appear long.

Locations Suited for Observations

Let’s observe from locations where you can see as wide an area of the sky as possible, where there are few streetlights.

In locations where it’s not possible to see much of the sky, such as in the woods, or a veranda where only a portion of the sky is visible, you won’t be able to catch meteors appearing over the entire sky. Please search for a site where you can see as wide an area of the sky as possible, with few objects blocking your view.

Also, you should choose a location with few streetlights or other artificial lights. The light from meteors is very dim compared to the brightness of streetlights, etc. If there is much artificial illumination, you won’t be able to see faint meteors overpowered by that brightness. This will reduce the number of meteors you can see.

In a large city or the surrounding area, the light from the entire city interferes with viewing the meteors, making it impossible to see faint ones. It's better to observe from locations as far away as possible from large cities.

Points for Observations

Meteors Video

This video, taken in the middle of the night of December 14, 2014, captured 7 of the Geminids meteors in the span of about 3 minutes, including one of startling brightness.

Reference Information

Meteors Explanation Movie
This movie explains about meteors.
International Meteor Organization
This page summarizes meteor shower observation information and observational results.
Totals for the 2017 Geminids
The observation results for the Perseids 2017 can be found here.
Special Astronomical Phenomenon Pages • Campaign List (Japanese language only)
A list of past special astronomical phenomenon pages and campaigns conducted by NAOJ.