Observing Meteor Showers

Meteors may be observed visually or photographically (video): both approaches require time and patience. While we may find sporadic meteors throughout the year, it is better to choose dates for which an annual shower is predicted, according to the calendar.

Placed conveniently, in a place that allows observing most of the sky, we just have to wait for meteors to appear. Most shall look like a small point of light that crosses the sky at high speeds. Others shall leave a trail, and may resemble these images captured by the "Calysteno" station (L'Hospitalet de Llobregat, Spain):

When we observe meteors coming from the same shower, if we trace back the meteor trajectory on the celestial sphere, we will see that all meteors appear to come (radiate) from a single point on the celestial sphere (actually, it is not a point but a small area): it is called the shower radiant. In order to verify whether an observed meteor pertains to a given shower, we will check whether its trajectory fits the expected radiant: if it does, and the meteoroid speed also matches what is expected, identification is positive.

It is important to remember that, in addition to meteors coming from showers, there are also sporadic meteors which are unrelated to them. Many sporadic meteors appear to come from a sporadic pseudo-radiant called the Anthelion Source, which has a wide radiant of elliptic shape (about 30° in right ascension and 15° in declination) located close to the anthelion (which is the direction opposite to Sun in the celestial sphere).

If you do not have experience in meteor observing, take into account the following:

• The percentage of illuminated Moon and its height over the horizon is critical. A near-full Moon located 30° or more over the horizon will make a very difficult observation, especially for faint showers.
• The height of the radiant over the horizon at the moment of the observation is also very important: the lower it is, the less meteors you will be able to see. Moreover, remember that showers with a clearly northern radiant are only visible from the northern hemisphere (or the southern hemisphere when declination is negative).
• You will be able watch much more meteors in the field, under totally dark skies, than in a big city.
• Do not attempt observing showers with ZHR rates under 30. Watch major showers first, and then gradually lower the ZHR level as you accumulate observing hours.