A Rare "Meteor Cluster" Over Aomori—19 Meteors in About One Second, Possibly a "World First" with the Perseid Meteor Shower

1. What Happened: 19 Trails of Light "Connected" in One Second

On August 13, 2025, around 12:57 AM, a surveillance camera installed at the "Hoshi to Mori no Romantopia Observatory 'Ginga'" in Hirosaki City, Aomori Prefecture, recorded 19 meteors in about one second flowing from northeast to southwest. This phenomenon is believed to be related to the active Perseid meteor shower. The video and article were published on Asahi Shimbun Digital, and the observatory's social media post received millions of views and tens of thousands of "likes." Asahi Shimbun+1

Key Points
・Date and Time: August 13, 2025, 00:57 (JST)
・Location: Hirosaki City, Aomori Prefecture (Romantopia Observatory "Ginga")
・Number: 19 in about one second
・Direction: Northeast→Southwest
・Parent Body: Perseid meteor shower (originating from Swift–Tuttle comet) Asahi ShimbunInternational Meteor Organization

2. What is a "Meteor Cluster"?

A meteor cluster is a phenomenon where several to a dozen meteors appear together within a few seconds. It was first reported during the 1997 Leonid meteor shower observation, and since then, there have been only about 10 reports worldwide, making it extremely rare. The mechanism is interpreted as meteor material in space splitting for some reason, and this **same "group of fragments"** entering Earth's atmosphere almost simultaneously, resulting in many meteors visible in a short time. Asahi ShimbunWikipediasubarutelescope.org

In the past, clusters have been confirmed in the Leonid meteor shower (1997/2001) and the September ε (Epsilon) Perseids (2016). For example, in the 2016 case, 9 meteors in 1.5 seconds were recorded, and it was analyzed that the probability of this occurring by chance was lower than 10⁻¹⁹. AGU Publicationsaanda.org

3. Why is it "Extremely Rare": Probability and Physical Background

Generally, the number of meteors in a meteor shower is discussed in terms of per hour. For example, the peak of this year's Perseid meteor shower was expected on August 12-13, and even under challenging moonlight conditions, an HR (Hourly Rate) of several dozen was anticipated. However, "19 in one second" is an outlier in the probability distribution, and it's natural to think that the "same parent body (same group of fragments)" entered consecutively. NAOJ and past research position clusters as direct evidence of meteor body fragmentation. National Astronomical Observatory of Japansubarutelescope.org

Why Does Fragmentation Occur?

• Thermal Stress: Temperature changes experienced when approaching or moving away from the sun

• Rotation and Centrifugal Force: Internal stress due to the rotation of small celestial bodies

• Micro Collisions: Fragmentation due to collisions between particles (also considered in SPE cluster analysis) ADS

4. The Academic Impact of This Event

Junichi Watanabe, a senior professor at the National Astronomical Observatory of Japan, has emphasized the importance of cluster phenomena since the first observation during the Leonid meteor shower (1997). This time, simultaneous observations in Fukaura Town and Hirosaki City, Aomori Prefecture are suggested, touching on the possibility of being the world's first for the Perseid meteor shower (verification in progress). If proven, it will be groundbreaking data for estimating the fragmentation timescale and spatial distribution of fragments within the dust stream originating from the parent body (Swift–Tuttle comet). X (formerly Twitter)

Additionally, international discussions continue regarding the definition and statistical criteria of cluster phenomena, and in 2025, a paper proposing **"definition refinement" by extracting candidate cases from existing databases has emerged. The Aomori case will likely become a latest, high-quality benchmark** that significantly advances this discussion. arXiv

5. Comparison with Past Cases

• Leonid Meteor Shower (1997/2001): Numerous cluster bursts were observed in various locations, drawing attention to fragmentation models. National Astronomical Observatory of Japanstargaze.co.jp
  
  

• September ε Perseids (2016): A cluster of 9 in 1.5 seconds was confirmed through simultaneous observations at two locations, statistically ruling out chance. aanda.org
  
  

• Mauna Kea, Subaru–Asahi Sky Camera (2021): The appearance of a "quasi-cluster" of several dozen in 10 seconds became a topic, reaffirming the importance of cluster research. University of Hawaii
  
  

This Time (2025, Aomori) is characterized by the high time density of "about 1 second, 19 meteors", and with the possibility of simultaneous observation at two locations, it is record-breaking. There are about 10 reported cases worldwide, making it stand out in terms of rarity. Asahi Shimbun