For reasons that are not very clearly understood, the nights around the spring equinox are a good time to observe bright meteors, also known as fireballs. Fireballs are defined as meteors that are brighter than the planet Venus.
Fireballs and meteors occur when the earth encounters bits of space debris – broken chunks of asteroids and decayed comets – in its path. These burn up during their passage through the earth’s atmosphere, producing a dazzling display in the sky.
On an average night, an observer might see 10-12 fireballs. But around the spring equinox, in the northern hemisphere, that number increases by 10 to 30 per cent.
This phenomenon has been known for over 30 years, but is still not understood. The cameras of NASA’s All-sky Fireball Network observe fireballs and by mapping their trajectories, can tell if they came from a comet, asteroid or low orbit human made space debris. This information is public and you can check to see if that fireball you saw last night is listed there.
Fireball season is different from meteor showers, which can be predicted accurately. The next will be the Lyrid meteor shower, which can be seen from April 16-25. A complete list of meteor showers for 2015 can be found here.
Arcturus rising in the eastern sky is another sign of spring. The brightest star in the constellation of Bootes the Herdsman, it can be seen around 9 pm as a bright star in the east-northeast sky in northern latitudes. The red giant appears orange to the viewer, and is the fourth brightest star in the night sky after Sirius, Canopus and Alpha Centauri.
The easiest way to spot Arcturus is to follow the arc from the handle of the Big Dipper, now high in the sky at nightfall. The name means “Guardian of the Bear” and may refer to the nearby constellations of Ursa Major and Ursa Minor. The Polynesians used Arcturus as a navigational guide. Its Hawaiian name is translated as “The Star of Joy”. Quite appropriate, as its appearance over the horizon indicates the beginning of a much awaited spring.