In the pleasant and brief nights of July, it is also the best time of the year to observe meteor showers. If you are interested in meteors, get ready to enjoy a visual feast.
After the annual two-month-long scarcity period of meteor showers, the peak season of summer meteor showers begins in mid-July.
Astronomers predict that meteor showers will appear consecutively in less than two weeks, including the Delta Aquariids and Alpha Capricornids showers, where the two will duel within each other’s range, and you may even see the crossing paths of lights. This is a dream come true for astrophotographers.
Just as they bid farewell to their annual performances, a third or even more dramatic cosmic dust flood will descend, namely the Perseids meteor shower, widely regarded as the most spectacular meteor shower of the year.
Here are some facts about the upcoming cosmic spectacle.
It is well-known that meteor showers cannot be predicted with great accuracy in terms of their exact numbers and timing, but their arrival during the peak season is undeniable. You can plan your schedule around them. The Delta Aquariids meteor shower will peak on July 29th to 30th, while the Alpha Capricornids meteor shower will peak on July 30th to 31st, perfectly aligned with each other.
According to AccuWeather, during the peak period, approximately 20 meteors per hour can be seen, but this is also difficult to predict. There may be many meteors before and after the peak season, as July meteors often persist steadily into early August.
The Perseids meteor shower will peak on August 11th to 12th, but many Perseids meteors may appear earlier or later. This famous meteor shower may produce as many as 100 meteors per hour at its peak.
Meteors are originally large space debris. Giant and ancient conglomerates of frozen gases, rocks, and cosmic dust fragments drift through space. For centuries, people on Earth have noticed that during certain calendar periods, we see meteors dancing in the night sky, as astronomers have discovered that they are fragments colliding with Earth’s orbit while passing through space.
When these space debris collide with Earth’s atmosphere, they ignite and display fiery streaks until they burn out. Astronomers have a good understanding of these dust conglomerates. Now, we know where they are, when to expect meteor showers, and even where these fragments come from: they are the debris left by comets.
Not all meteor showers are the same. The Delta Aquariids and Alpha Capricornids showers are one of the meteorological wonders of the entire calendar year. They may not be as awe-inspiring as other meteor showers, but the warm July nights with two meteor showers this month make summer nights truly worth anticipating.
Although the Delta Aquariids shower is rich in faint meteors produced by smaller particles, about 5% to 10% of them will leave glowing gas trails known as persistent trains, which can last for several seconds. According to data from the Astronomical Society, the Alpha Capricornids shower often produces a large number of slow-moving, bright, and colorful meteors.
When it comes to meteors, slow and fast are relative terms. The “slower” Alpha Capricornids shower moves at an average speed of 15 miles per second, while the Delta Aquariids shower has a moderate speed exceeding 25 miles per second.
We make wishes when we see meteors. But how many of us wonder where they come from in heaven? We can be sure that meteors add a touch of brilliance to our sky every late July, and equally certain is that we can precisely locate their invisible points of origin on star maps.
They are named after constellations. The Delta Aquariids meteor shower seems to radiate from a point in Aquarius, hence its name the Aquariids shower. The Alpha Capricornids meteor shower points toward a spot near Capricorn—just a few degrees south of Aquarius—thus it is called the Capricornids shower.
The point from which meteor showers radiate is called the radiant point. The two radiant points will rise in the direction from south to southeastern.
However, the radiant points do not reveal where we can find them. Astronomers suggest not observing the radiant points themselves, but scanning the entire night sky as much as possible.
This is because meteors that fly directly into your line of sight from the radiant point will approach at an angle no greater than zero. Would you say it’s easier to find a needle from the side rather than head-on? Meteors with angles greater than zero (e.g. 45 degrees) will reveal their long sides. Therefore, you will see a fragment of light rather than a pinpoint. It may appear anywhere in the sky but not at the radiant point.
As the two radiant bodies are so close, it may be difficult to distinguish between the Alpha Capricornids and Delta Aquariids showers. They may even intersect. With enough technical know-how, people can trace them back to their respective radiant points, or estimate who they are based on their “slow” or “fast” speed, but it’s easier said than done.
In late July, those wishing to see the meteor showers should search the sky from evening until midnight. Typically, the best time to observe meteors is before dawn (from midnight until the predawn), but due to light pollution caused by the waning moon, astronomers suggest watching before moonrise is best.
Although July nights are shorter and meteors may not be as easily seen, the pleasure of summer meteor watching is unparalleled.
Don’t forget to make a wish!