Over the past three and a half months, the night sky featured very few shooting stars for anyone on Earth to observe. Such a “meteor drought” as this happens every winter, but it will soon end.
We’re entering the spring meteor season.
In April, astronomers will train their telescopes skyward and find fireballs spewing from the northerly constellation Lyra the Harp, high in the dome of the sky.
The Lyrid meteor shower, named after constellation Lyra and famous for its uncommon outbursts of up to 100 meteors per hour, appears within a short window every year in late April.
How to Spot the Lyrids
Under perfect darkness, when there’s no moonlight, the Lyrids will typically yield between 10 to 15 meteors per hour. Adding to their drama, roughly a quarter of them will leave spectacularly long streaks of ionized gasses trailing behind, the technical term for which is “persistent trains” or, more colourfully, “fireballs.”However, this time around the Lyrids will face some stiff competition, as the last quarter moon falls on April 20, meaning a rather broad, waning crescent moon will partially steal the show by drowning out some of the meteors.
Hopeful viewers should wait for the radiant to rise by midnight. Vega will be high in the sky’s dome just before dawn. That’s the best time for viewing.
How the Radiant Works (and Other Lyrid Tidbits)
A curious observer may wonder why the Lyrids seem to radiate from a fixed point inside Lyra—a constellation dozens of light-years away—when clearly these meteors are burning up in our atmosphere a few kilometres above the Earth. The answer can be summed up in a word: perspective.To unpack that, we must first understand what meteors are and how they exist in space. They’re just frozen chunks of gas and cosmic dust left over from larger space objects like comets or asteroids. And since these parent objects orbit the sun, so do the meteors following in their wake, implying that meteors travel in parallel along a vast loop around the sun.
So, perspective comes into play when they fly towards us on a dark night and appear as shooting stars. It’s like how train tracks travelling in parallel seem to converge on the horizon due to a trick of perspective. Meteors likewise travel in parallel and seem to converge on a distant point—the radiant.
Also, like train tracks fixed on the ground, the orbit of these meteors is fixed in space, which also fixes the radiant with respect to distant stars. So that’s why the radiant is fixed near Vega.
The existence of this debris stream also explains why the Lyrids appear at the same time every year consistently; the stream intersects with our orbit, and Earth ploughs through every year like clockwork.
Where Do the Lyrids Come From?
One of the earliest Lyrid sightings dates to the Spring and Autumn Period of ancient China (from the late 8th to mid-4th centuries B.C.), when meteors were observed falling like rain.But more recently, in 1861, Western astronomers noted its parent object, Comet Thatcher, for the first time. It had reached its closest point to the sun, or perihelion, which caused it to light up brilliantly due to being energized by the sun’s radiation.
Near perihelion, comets exhibit their characteristic tails as their frozen matter sublimates into gas and they begin to shed their matter into space, leaving vast complexes of debris spanning millions of kilometres.
We will never see Comet Thatcher again, nor will our children. Astronomers calculated that its orbit reaches outside the solar system, 110 astronomical units away, and requires 415 years to circumnavigate once. It will reach its furthest point from the sun in 2070 but won’t reach perihelion again until 2283.
The Lyrids are a different story. The vast dust stream spawned by Thatcher is omnipresent and will faithfully break Earth’s winter meteor drought every year in late April.
