Lyrids meteor shower culminates on Thursday and Friday. They will be followed by a "supermoon""

  • Tomáš Lanča
  • 17.05.2021
On Thursday 22nd and Friday 23rd April, in the early morning, it will be possible to watch the most meteors from the annual meteor shower in Lyrida. These popularly called "shooting stars" are in the Earth's atmosphere caused by the extinction of ice-dust particles released from the core of Comet C / 1861 G1 (Thatcher). During the maximum, 10-15 meteors can be seen in the dark sky far from large cities and harmful light pollution, always in the early morning hours before dawn. Less than a week later, we are also waiting for one of the two angularly largest full moons of the year.

A meteor shower is a phenomenon in which a stream of interplanetary dust particles (expertly meteoroids) crosses the Earth's orbit, and these particles then rub against air molecules as they pass through the Earth's atmosphere, gradually evaporating and forming a glowing trail. There are flashes, which are technically called meteors, popularly "shooting stars".

Meteors from the constellation Lyra

The name of the swarm of Lyrida comes from the name of the constellation Lyra, from which meteors seem to fly for most of the swarm's activity. In the case of Lyrid, this place - radiant - lies about 8 degrees west of one of the brightest stars in the sky - Vega from the constellation Lyra. In the April sky, the constellation Lyra rises high above the horizon with a bright star until morning, however, it is partially observable all night. At the time of the swarm maximum, ie at the end of April, it is at most after 5 o'clock in the morning, ie at dawn. The radiant of a meteor swarm in our latitudes will reach a height of over 70 ° above the horizon. Thanks to this, a maximum swarm can be observed in the Czech Republic with a frequency of up to 15 meteors per hour in the early morning hours (then most meteors shine above the horizon, only a few below it).

Long-period comet and occasional "meteor showers"

The first reports of a swarm of Lyrida date back to 1863, when astronomers associated the swarm with Comet C / 1861 G1 (Thatcher). It was the comet's return in 1861 and the subsequent extraordinary increase in activity of the Lyrida swarm two years later that forced astronomers to look for further observations of this swarm in the past. It turned out that a very significant manifestation of Lyrid took place as early as 1803, the earliest historical observation dates back to March 23, 687 BC in China. It is thus the longest-recorded swarm in the history of mankind. The comet itself returns to the Sun once in about 415 years, the next generation will not return again in 2283.

The swarm is known to occasionally provide significant "showers". From the normal low frequency of meteors (10-15 per hour), activity will rise sharply to several hundred meteors per hour. This was the case in 1803, when the clock frequency rose to 700 meteors. In the 20th century, similar cases occurred in 1922 and 1982. A slightly smaller increase in activity occurred in 2000. Astronomers anticipate that a similar increase in Lyrid activity will be seen in the 21st century, as well as in the following decades. However, for a more accurate prediction, a more thorough observation of the Lyrids at each maximum is needed - precisely accurate monitoring of the swarm activity allows better modeling of the density of the dust particles that the Lyrids cause.

Rather poor conditions this year

Lyrids have rather worse observational conditions this year. The maximum is predicted for April 22 at 3 pm Central European Summer Time, ie in broad daylight. Fortunately, Lyrida is one of the swarms that do not have a very sharp maximum, so the increase in its activity can be observed even a few hours before or after themaximum. The earth begins to flow through a stream of meteoroids on April 16, and activity gradually increases over the next few days. The last swarm meteors can still be seen on April 25. The swarm is therefore worth observing, especially in the morning before or after the maximum. Due to the bright glow of the Moon and the height of the swarm's radiant, it is best to observe Lyrids on Thursday 22nd and Friday 23rd April, always between 2 and 5 o'clock in the morning. Significantly better conditions will not occur until 2023.

To observe the swarm, choose a place with as little trees or buildings as possible for a good view, but above all as far as possible from light pollution from cities (you will also see weaker meteors). The phenomenon is best observed lying down - so we recommend a lounger or mat. However, it is necessary not to underestimate the cold April nights, so equip yourself with the warmest possible clothes, sleeping bag or a few blankets. During the nights of April, it is also necessary to take into account the possible occurrence of inversions, so it is best to go to the mountains. Furthermore, nothing is needed - meteors fall randomly across the sky. So just stare at any area of the sky and wait for the first meteor to flash.

Easy target for photographers

You can also photograph the phenomenon. However a compact camera will definitely not be enough. First of all, you need to place the camera on a tripod and aim it at a selected part of the sky. Your camera must be able to take several seconds of exposure (or allow you to manually control the shutter at any time, generally indicated by the letter "B"). If your photographic equipment meets these requirements, then simply point the lens at the sky at random during the night, open the shutter (or run as long exposure as possible) and wait for a brighter meteor to fly in the star field your camera is currently capturing. In the image, it then appears as a narrow light trail, sometimes with occasional brightening. Of course, a great advantage can be a light wide-angle lens, which does not reflect the rotation of the Earth too much at shorter exposures (stars will not appear as small arcs, but points) and occupy most of the sky, thus increasing the chance of capturing a meteor trace. Apart from meteors, the summer Milky Way and the planets Jupiter with Saturn can also be seen in the early morning hours.

For the rest of the spring, two "supermoons" and dust from Halley's Comet

Other interesting phenomena await us by the end of April and in May. On Tuesday, April 27, at 5:33 CEST, there will be a popular "supermoon" - the moon will be full and at the same time close to the Earth's surface (this will take place less than 11 hours later at a distance of 357,378 km). The full moon will be angularly one of the largest angularly this year.

The meteor shower of η-Aquarida culminates in the flower sky. Specifically at night 5. / 6. May 2021, when the swarm will peak early in the morning (around 5 o'clock in the morning) and the Moon will be in phase only 5 days before the new Moon, so it will almost not be disturbed by its light. Meteors are relatively fast and fly at a considerable frequency, but unfortunately rather over observers near the equator. In our country, the constellation Aquarius, in which the swarm's radiant lies, rises just low above the horizon in the second half of the night, so we can see about 10 meteors per hour. The vanishing ice-dust grains come from famous Halley's comet.

The full moon on Wednesday, May 26, will occur at 1:15 pm (when a total lunar eclipse will take place at the same time, unfortunately below the horizon in our country) and will be angularly the largest this year. However, the moon will be closest to Earth at 3:53 in the morning (ie in the early morning hours before sunset) at a distance of 357,309 km. So before the moon set early in the morning, we will observe the popularly called "supermoon". However, the sunrise will be just as beautiful shortly after the full moon of the evening.

The maximum of the meteoric swarm of Lyrida in 2020 over the Seč dam with the marked constellation Lyra, the star Vega and the radiant of the swarm. Photo: Petr Horálek.
Maximum meteor shower of Lyrida in 2020 over the Seč dam. Photo: Petr Horálek.
Comparison of the angularly largest and smallest full moon in 2018. Photo: Petr Horálek.
The rise of the May full moon behind Kunětická hora near Pardubice. Photo: Petr Horálek.