Notes on the Meteor Shower Forecast

The Meteor Shower Forecast uses your computer's clock and calendar and observations of meteor showers in the past to calculate whether or not there is currently a meteor shower going on.  The values given by the forecast represent average values and may vary from time to time.  The "shower" box displays the name of the shower.  The "# per hour" box displays the average number per hour seen historically when the shower is at or near peak.  The "radiant" box displays the position of the radiant in right ascension (RA) and declination (Dec).  Around the shower's peak, a graphic will be displayed to show you constellations near the radiant and where you should look at a particular time.

The time of observing and Moon conditions are two important factors that need to be taken into consideration when observing meteors.  The best time to observe meteors is generally between 10 p.m. and dawn.  More meteors hit the Earth on the side that faces the Earth's direction of travel along its orbit.  This occurs after midnight (see diagram below).  Very few meteors can catch up with Earth on the other side.  Therefore, most meteors and most meteor shower radiants rise after midnight. 

Figure 1:  The yellow lines represent the paths of meteors.  As you can see, most meteors strike the right side of the planet in this diagram.  This is the side of the Earth that is sweeping out the stream of meteors.  On the back side, few meteors have enough velocity to reach Earth.  This does not mean that meteors cannot be seen on this side.  Meteors can even be seen in daylight if they are bright enough. 

The Moon can make meteor watching unbearable if it is at or near full phase.  If the Moon is more than half illuminated from our point of view, only the bright meteors will be visible.  Otherwise, even with a cresent moon, meteor observing is not difficult.  That is why I have included both time calculations and Moon calculations in this forecast.  While the time and Moon calculations are fairly accurate, other conditions may effect viewing of meteors such as weather, the Earth's position, and time since the last pass of the comet or asteroid that causes these meteor showers. 

For amateur radio operators interested in meteor scatter, please check http://www.nitehawk.com/rasmit/ws1_15.html.