(Machine translation by DeepL + adjustments by Gyegyopon, Translated article written for Japan without major changes, Sorry for Japanese language left in diagram etc.)
Hello, this is Gyegyopon.
The Perseid meteor shower, which is active in mid-August, is one of the “three major meteor showers” and you can see many meteors every year without missing a beat.
If you go to a place with a good view of stars, you can see a lot of meteors, or you may be able to see meteors even in the bright sky of a city.
This article summarizes the status of the Perseid meteor shower in 2023 and information about meteors.
I hope this article will be helpful for those who want to see meteors and learn more about meteors.
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If you want to know the status of the Perseid meteor shower this year quickly, please read “Summary“.
“What is the Perseid Meteor Shower?” and after that, the contents of “Summary” are explained in a little more detail.
If you want to know more about meteors, please continue reading “What are meteors?“
Summary
The Perseid meteor shower in 2023 should be viewed on any (or all) of the four nights from the night of August 11 through the morning of August 15, with the greatest number of meteors expected to be visible before dawn on August 14, and a significant number expected to be visible before dawn on August 13. If you are in a dark sky, you can expect to see more than 30 meteors per hour when the most meteors are visible.
In all cases, a good number of meteors will begin to appear around 9:00 p.m., and the number of meteors will increase as dawn approaches after midnight.
Don’t worry about where in the sky to look. Meteors can appear in many different directions.
The best place to view meteor showers is where the sky is dark and you have a wide view of the sky. It is best to stay as far away from large towns as possible.
What is the Perseid meteor shower?
The Perseid meteor shower is a meteor shower that is active in mid-August every year. The Perseid meteor shower is one of the three major meteor showers, which are the three meteor showers where you can see a lot of meteors. The other two meteor showers are the Quadrantid meteor shower in January and the Geminids meteor shower in December.
The Perseid meteor shower is stable, with many meteors appearing every year1. And it is an “easy to see” meteor shower because it is “seen in the warmer months” and “in the middle of summer vacation”.
However, the fact that most of the meteors are visible from after midnight to before dawn may make it a little more difficult.
Perseid meteor shower this year
The maximum activity2 of the Perseid meteor shower in 2023 is expected to be around 17:00 on August 13. Since the Perseid meteor shower will be visible best in Japan during the pre-dawn hours, the best time to see many meteors will be before dawn on August 13 and 14.
It is expected that more meteors will be visible before dawn on the 14th than before dawn on the 13th.
You can also expect to see a certain number of meteors one day earlier, before dawn on the 12th, and one day later, before dawn on the 15th.
In the darkest areas of the sky, the highest number of meteors is expected to be over 30 meteors per hour.
(This does not depend on the year.) Meteors of the Perseid meteor shower tend to begin to appear around 9:00 p.m. and increase in number after midnight and toward dawn. (This may be a little hard for those who are not good night owls.)
However, this does not mean that meteors cannot appear even before 9:00 p.m., so it is a good idea to observe them even in the early hours without giving up.
This year, the moon rises before dawn during the days of the maximum; if it is August 14, the moon rises around 2:30 p.m.3. Faint meteors will be obscured by moonlight, but since the moon is quite thin (dark) this year, it is not likely to be much of a problem.
Still, more meteors may be visible before the moon rises than after.
Directions in which meteors are visible
Meteors can appear in various directions in the sky. Despite the name “Perseid meteor shower,” meteors do not appear only in the direction of the Perseids.
There is a characteristic in the way meteors appear in meteor showers.
Meteors appear radially outward from a point in the night sky called the “radiant point”. It is called the “Perseid” meteor shower because the radiant point is located near the constellation Perseus.
Meteors that appear near the radiant point are moving toward us, so their paths are short and they move slowly. Meteors that appear some distance away from the radiant point have longer and faster paths because they are moving sideways.
If you find a meteor in the night sky and it is moving outward from the radiant point of the Perseid meteor shower, it is very likely that it is a Perseid meteor4. Conversely, meteors moving in an otherwise direction are not meteors of the Perseid meteor shower, even during the active period of the Perseid meteor shower.
How to observe meteors
To see many meteors, watch them in a place where the sky is as dark as possible (you can usually see many stars). If the sky is bright, dark meteors will be obscured by the brightness of the sky, and the number of meteors you can see will be reduced.
As for where the “dark sky” is, roughly speaking, the further you are from a large city, the darker the sky will be. The sky becomes darker the further you are from a large town, because there is a lot of artificial light in a large town, which illuminates the sky and makes it brighter.
Even when observing in the vicinity, it is a good idea to find a place with as few lights nearby as possible.
It is also important to have a wide view of the sky. Meteors appear in various places in the sky, so if you have a wide view of the sky, the probability of meteors appearing there will increase.
You do not need any special tools to observe meteors. Observe with the naked eye.
If you use binoculars or a telescope, your field of view (the area you can see) will be very narrow, which is not good for catching meteors that may appear anywhere in the sky.
It takes time for your eyes to get used to the darkness. It is a good idea to let your eyes adjust for about 15 minutes after you go to a dark place. During that time, try not to look at anything bright, such as a smartphone screen.
It is very tiring to stand and look up all the time.
It is easier to observe by lying down on a leisure sheet or something similar. (Try your best to sleep during the day so you don’t fall asleep.)
Don’t forget to take precautions against mosquitoes and other insects5. You can’t concentrate on watching meteors if you are worried about insects.
Shouting or going into places you are not supposed to go at night can cause trouble, so be sure to observe rules and manners. Also, since you will be working in the dark, be careful of accidents.
What is a meteor?
Here is a little more detailed information.
A meteor is a phenomenon in which dust particles, like grains of sand flying through space, fly into the earth’s atmosphere at high speed and shine.
Meteors in meteor showers are based on dust grains ejected from a single comet. In the case of the Perseid meteor shower, the comet that emitted the dust grains (called the “mother comet”) is Comet Swift-Tuttle (109P/Swift-Tuttle). The dust grains ejected from the comet are spread throughout the comet’s orbit, and when the Earth passes through it each year, the dust grains plunge into the Earth’s atmosphere6.
This is why the same meteor shower meteors appear at the same time each year.
Since all the dust grains fly in from the same direction and come toward you, the meteors appear to radiate from a certain point. The central point from which meteors radiate is called the “radiant point”. The radiant point is conceptual (thought up in your mind), so if you look closely at the night sky, you will not see anything there.
If a meteor happens to appear at the radiant point, it appears as if light appears and disappears without moving. Such a meteor comes straight toward you.
Number of Meteors Visible
The number of visible meteors depends on the activity of the meteor shower itself, the altitude of the radiant point and the brightness of the sky at the location where you observe.
Activity of the meteor shower itself
Dust grains spread over the comet’s orbit have denser and less dense parts. If the earth flies into the dense part, many dust grains will fly into the atmosphere and many meteors will appear.
The increase in the number of dust grains entering the atmosphere and the number of meteors that appear is expressed as “increased activity of meteor showers”.
Roughly speaking, dust grains encircle the orbit of a comet in a cylindrical shape, with the dust grains becoming denser toward the center. Therefore, when the earth approaches the center of the dust grains, the activity of the meteor shower becomes more active, reaching a maximum at the densest part, and after the maximum, the dust grains gradually become sparser and the activity of the meteor shower calms down.
Altitude of the radiant point
If the activity of the meteor shower is the same, the higher the altitude of the radiant point, the more meteors will appear.
Meteors in the Perseid meteor shower begin to appear around 9:00 p.m., and the number of meteors tends to increase from after midnight to dawn, because the altitude of the radiant point gradually increases.
One of the reasons why the number of meteors increases as the altitude of the radiant point rises is due to the difference in the range over which the same number of dust grains fly into the sky.
Let us compare the case where the same number of dust grains come from directly from the zenith and the case where the same number of dust grains come from oblique angles. When the dust particles come at an angle, the same number of dust particles are spread over a larger area. Therefore, fewer meteors will be visible7.
Meteors do not appear when the radiant point is below the horizon8.
Brightness of the sky
The darker (where you can see darker stars) the sky is, the more meteors you will see. Conversely, when the sky is bright enough that dark stars are not visible, the number of meteors seen will be less because dark meteors will not be visible.
In addition to differences in sky brightness depending on location, the moon also affects the brightness of the sky.
When the moon is very thin, it has little effect, but the thicker the moon is, the brighter the sky becomes. The sky is brightest around the time of the full moon, and the sky lit by the full moon will be so bright that only fairly bright meteors will be visible.
In the case of the Perseid meteor shower, the number of visible meteors is more than doubled when observed in a sky where stars up to one magnitude fainter are visible9.
Unexpected appearances in 2021
The normal maximum of the Perseid meteor shower in 2021 was around 4:00 a.m. on August 1310. And as expected, many meteors appeared around that time. However, a day and a half later, around 17:15 on August 1411, there happened more than twice as active (sudden appearance) as the normal maximum.
This outburst was also captured by a live camera located near the Subaru Telescope in Hawaii. This live camera was installed in April 2021 and broadcasts the Hawaiian sky over the Internet 24 hours a day. Because of the bad weather in Japan at that time, many people watched this live camera and saw many meteors appear later than the normal maximum.
If the sudden appearance in 2021 were to occur at the same time this year, it would be at 5:00 a.m. on the 15th. The sky will already be light at this time, so if you observe at 3:00 before the sky becomes light, you may be able to catch the beginning of the prominence.
Unfortunately, however, no sudden appearance was seen at the same time in 2022, and it is thought that no sudden appearance will occur this year, 2023.
Nevertheless, we will not know what will happen until we actually observe it. If you continue to observe even at off-maximum times and dates, you may be able to catch an unexpected occurrence.
Other predicted sudden appearances
The sudden appearance in 2021 was not expected at all, but there are other sudden appearances that are expected this year.
An abrupt appearance due to a dust grain ejected in 68 BC is expected around 10:00 to 11:45 on the 14th. Another outburst is expected around 10:00 on the 13th. However, since it is daytime in Japan, even if the meteors appear as expected, unfortunately, we will not be able to see the increase in meteors in Japan.
Related Information
Reference
- National Astronomical Observatory of Japan: Perseid meteor shower will reach its maximum (August 2023)
- Mikiya Sato: Information on the Perseid meteor shower in 2023
- IMO (International Meteor Organization): 2023 Meteor Calendar (projected sudden appearance, magnitude ratio)
- Subaru Telescope: Subaru Telescope’s Live Camera captures the Perseid meteor shower
- National Astronomical Observatory of Japan/Asahi Shimbun: Subaru Telescope Live Camera
- AstroArts:
- Unknown maximum of the Perseid meteor shower that came a day and a half late
- Monthly Star Navi November 2021 issue, “Perseid meteor shower: 1.5 days late sudden appearance”, December 2021 issue, “Surprising junior high school student research: Mauna Kea live video records Perseid shower sudden appearance”
- Asahi Shimbun Digital: Second-year junior high school student independently discovers large appearance of shooting stars, expert “moved to tears”
- Shigeo Uchiyama: Aggregate Calculation Method of Visual Observation of Meteors (Difference in the Number of Meteors by the Altitude of the Radiant Point)
- National Astronomical Observatory of Japan: Calculation of almanac (time of moonrise and sunrise in each region)
Others
Change History
(August 6, 2023) Added a figure comparing the case where dust particles fly into the atmosphere from directly above and the case where they fly into the atmosphere from an oblique angle. The annotations have been slightly rewritten for clarity.
(August 9, 2023) Measures against insects were added to “How to observe meteors”.
脚注
- The Geminids meteor shower is also stable. The Quadrantids meteor shower is hit or miss from year to year.
- This refers to the time when the meteor shower will be most active and the time of the maximum activity. The
- The time of moonrise and the time when the sky begins to lighten at dawn varies from place to place. This article describes the time in Tokyo, but the time is not much different in other areas. For example, moonrise on August 14 is at 2:27 in Tokyo and 2:48 in Osaka.
- Since it is possible that a meteor that is not a Perseid meteor shower will move in the same direction by chance. This is not a 100% reliable method of identifying meteors.
In order to identify meteors with certainty, we observe meteors from two or more places and determine their three-dimensional paths and velocities based on the principle of triangulation. If the original dust grain has the same orbit as the mother comet, we can determine that it is a meteor from that meteor shower. - Gyegyopon often uses mosquito coils (katori senko) because Gyegyopon is not good at putting something on the skin. (Not that Gyegyopon recommend it. Use your best judgment depending on your situation.) If you place mosquito coils in four places around you, they will protect you from insects no matter which way the wind blows. Please be careful with fire.
- So only comets whose orbits intersect with the Earth can be the mother comet of a meteor shower.
- If the altitude of the radiant point is θ degrees, the area over which the same number of dust grains fly into is (1/sin θ) times larger than when the radiant point is at zenith (directly above your head).
This means, for example, that if the altitude of the radiant point is 30 degrees, the area of the atmosphere over which the same number of dust particles can fly into is twice as large, thus halving the number of meteors. (The right side of Figure 2 is drawn with the radiant point altitude as 30 degrees.) - , but when the radiant point is just below the horizon, meteors may appear, though in very small numbers.
- The luminosity ratio is a numerical expression of how many times more meteors are visible when stars up to one magnitude fainter are visible. For example, suppose you observe a meteor shower with a magnitude ratio of 2, and you see 10 meteors in the sky where you can see stars up to 3rd magnitude (as the faintest stars). If you observe it in the sky where you can see up to 4th magnitude stars, you can expect to see 10 x 2 = 20 meteors, and in the sky where you can see up to 5th magnitude stars, 10 x 2 x 2 = 40 meteors.
The luminosity ratio of the Perseid meteor shower is 2.2. - The Perseid meteor shower reaches its normal maximum around 140.0 degrees solar ecliptic longitude every year. The name “solar ecliptic longitude” is “solar…” but you can think of it as indicating the position of the earth around the sun. It is the angle, centered on the sun, of how far the earth has moved from a specific location, the vernal equinox, due to its orbit.
- It is near 141.479 degrees solar ecliptic longitude.
