Evening Meteor Observing
Observing meteors in the evening can be a rewarding time. Evening rates of meteors are not as high as that of early morning hours, but none the less has its share of activity. Meteor rates start of low in the evening and rise gradually during the night to a peak in the early morning before astronomical twilight. This diurnal variation can be observed every night.
The reason for meteor rates being lower in the evening than the morning can be explained. In the evening the observer is on the trailing hemisphere of the Earth relative to its motion around the Sun. The sporadic meteors you see are the result of meteoroids catching up with the Earth from behind. The mass of the Earth is between the observer and the head on collisions of meteoroids on the leading edge of the Earth’s rotation. By the time early morning hours come around, the observer has been carried around to the leading edge and is encountering meteoroids swept up as the earth plows through the zodiacal dust cloud. To visualize this, imagine traveling in a car in a gently rainfall. The leading edge or front of the car encounters heavy rain while the back or trailing edge encounters little or no rain.
Evening meteors as well as being less frequent are normally slower and as a result not as bright. This is not always the case. On many evenings you will see a nice slow meteor that is quite bright. This is quite spectacular as you have the opportunity to have a good look at it. Evening meteors can last many seconds, and generally their slower speed allows them to penetrate lower into the atmosphere. This alone can introduce certain unpredictability into the meteors flight. The chance of the meteor splitting into two or more paths or exploding (brighter meteors as bolides) increases. Personally I have seen my most memorable meteors in the evening including many fireballs.
There is much scientific work that can be done in the evening. Meteor stream activity, due to the general lack of hours of observing participated in during the evening, is not well known. Around 70 % of all observing in done in the morning hours, the general belief being that if you are not seeing as many meteors the results area not as good. This is not so. Hours of observing where the rates are low, as long as they are accurate are just as valuable to scientists.
Evening observing also provides a good time to observe on weekdays where it is hard to stay up late and observe in the morning when you have to work the next day. This is the case for a number of our observers and they are finding evening observing quite rewarding from that aspect. Observing in the evening is better than no observing.