National Astronomical Observatory of Japan

Peak of the Perseid Meteor Shower (August, 2017)

Photograph of Perseid meteor shower
Maximum resolution(6000 x 4000)

Let’s Look for the Perseids Too Bright to Lose to the Moonlight!

The peak (note 1.) of the 2017 Perseid meteor shower is expected to occur at 4:00 on August 13, Japan Standard Time.
This is a perfect time to observe in Japan. Also, the best time to see the Perseids in Japan will be around midnight on the 12th to dawn on the 13th. This year, the number of meteors is predicted to be around 35 per hour at the time when the most meteors can be seen, if observing under a dark sky. This is slightly less than usual because the bright Moon is shining the whole time.

Shooting stars don’t appear in a set direction. Please observe so that you can see a large area of the sky without the Moon coming into your field of view.

Let’s search for the meteors too bright to lose to the moonlight!

(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, and the conditions of the Moon. Back

For further information about the Perseids, please see below.

About the Perseid Meteor Shower

The Perseid meteor shower is a meteor shower which is active around August 12 and 13 each year.

The Perseid meteor shower is a very easy meteor shower to observe.

One of the reasons is because it is almost guaranteed that many meteors appear every year. It is known as one of “The 3 Major Meteor Showers,” along with the Quadrantids in January and the Geminids in December. When the conditions are good, you might observe over 40 per hour.

Also, because the active period of this meteor shower overlaps with the O-Bon holidays in Japan and summer vacation for many people, it is easy to stay up late and the meteor shower provides a reason to go someplace where the stars can be seen clearly.

Furthermore, the active periods of the “Quadrantids” and the “Geminids” fall in the cold winter season, but the active period of the Perseids falls in the lush summer time, so we don’t need to worry much about the cold during observations.

To Observe the Perseid Meteor Shower

Here we have collected information which could prove useful for observing this year’s Perseid 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 the 12th until dawn on the 13th.

It is also thought that many meteors will be visible from the night of the 13th to dawn on the 14th.

The peak of the Perseids is predicted to occur around 4:00 on August 13, Japan Standard Time. At that time, the Perseids’ radiant point is at a high position as seen from Japan. Therefore, it is expected that many meteors will appear. It’s predicted that the most meteors will appear from the night of the 12th until dawn on the 13th.
Furthermore, it’s not exactly at the peak time, but from the night of the 13th until dawn on the 14th, it is thought that many meteors should appear, but not as many as on the peak night.

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.
From roughly August 7 to August 15, the Perseids continue to be relatively active, so we think it should be possible to see more meteors than normal. However, as we move away from the day of the peak, the number of meteors which will appear decreases. The total active period of the Perseids is thought to last even longer, extending from around July 17 to August 24.

Time Period Suited for Observations

It would be best to observe between midnight and dawn as much as possible.

(For constant meteoric activity) the higher the elevation of the radiant point, the more meteors will appear. For the Perseid meteor shower, the meteor appearance conditions in each time period are as follows.

Before 21:00
Because the radiant point is still positioned low near the horizon, not many meteors will appear.
21:00 to Midnight
The elevation of the radiant point gradually rises and meteors begin to appear.
Midnight to Dawn
The elevation of the radiant point continues to increase, reaching its maximum before dawn. The number of meteors that appear increases along with the elevation of the radiant point. The most meteors will appear before the sky starts to get light.

The Effects of Moonlight

Around the few days before and after the peak of the Perseids, the bright Moon shines around the appropriate time to observe. When observing, make sure that the Moon is not in your field of view.

This year the full moon falls on the 8th and the last quarter moon falls on the 15th. For several days around the 13th when it is thought the number of meteors should increase, the Moon rises before midnight which is the start of the time suitable for observations. The waning gibbous moon is bright, and while the Moon is in the sky, the dim meteors won’t be visible in the moonlight. Since the Moon doesn’t set until the day breaks, it will be difficult to avoid the moonlight this year.

Observing the Perseids when there is moonlight like this year, it is best to observe in a direction where the Moon will not be in your sight and hope for meteors bright enough to standout in the moonlight.

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

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 more than 35 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 to the naked eye.)

If you observe from inside 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 Perseids

If it is possible to watch a large area of the sky, it doesn’t matter what direction you look. Please make sure that the Moon is not in your field of view.

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

Meteors appear to radiate around the central point of the meteor shower. This central point is called the “radiant point.” For the Perseid meteor shower, the radiant point is near the γ (Gamma) star of the constellation Perseus.
This is not to say that meteors appear only around the constellation Perseus 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.

This year, it seems that you might often observe in the moonlight. If the Moon is in your sight, its brightness will make it hard to see the dim meteors. Let's observe the Perseids in a direction so that the Moon will not be in your sight.

During the period when the Perseid meteor shower is active, meteors other than the Perseids also appear.
To determine whether it is one of the Perseids or not, please follow the meteor trail backwards and see if it passes through the radiant point of the Perseids. If it doesn’t point back towards the radiant point, it isn’t one of the Perseids; if it does, it is highly probable that it is one of the Perseids.

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, etc.

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. It 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

  • Specialized equipment, like telescopes or binoculars, is not required. You should observe with the unaided eye. When using a telescope or binoculars, your field of view narrows drastically, so this equipment is not suited for meteor observations.
  • If you observe for long periods while standing, your neck will get tired. It is best to prepare a picnic sheet so that you can observe while lying down.
  • After going outside, your eyes need to adjust to the darkness, so please observe for at least 15 minutes.
  • As with any outdoors activity late at night, please be careful to avoid accidents.
  • Please use good manners: do not use loud voices near people’s homes, do not enter off-limits areas, etc.

Meteors Video

Please take a look at this video of the Perseids taken on August 12, 2016.

Reference Information

Meteors Explanation Movie
International Meteor Organization
This page summarizes meteor shower observation information and observational results.
Totals for the 2016 Perseids
The observation results for the Perseids 2016 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.