Every year we get lots of enquiries and reports from people who have seen things in the sky. Most of these “lights in the sky” are quickly identified as astronomical objects, such as bright planets. Sometimes they are bright stars, but seen under unusual circumstances. Then of course there are manmade events, such as the re-entry of space debris into the atmosphere, where it burns up, or the brilliant flashes of reflected sunlight from the antennas on the Iridium satellites. These events, called “Iridium Flares”, are amazing things to see. However, there are sightings we are unable to tie down to anything familiar. Unfortunately the majority of these are due to incomplete data, such as uncertain dates and times, no usable direction information, and limited descriptions of what was observed. Discerning the characteristics of bright objects against a dark sky is not easy, for any of us.
The cardinal rule, which experienced observers are very familiar with, is to note everything possible about the event, including time, date, location etc., and to get it all written down with the minimum of delay. If it is something truly unusual, report it to others promptly, so that all the reports can be brought together while the trail is hot, and if necessary, observers can be contacted for further information before the details get confused or forgotten. There are very few people who can retain detailed information for long periods without the memory becoming distorted. As we try to make sense of what we saw, our minds obligingly slowly change the memories to fit. This is a real shame, because there are almost certainly new things awaiting discovery, and a delay before getting the information written down can render a report largely useless. Here are some rules of thumb.
As soon as possible after the event, write down what you saw. Start with the date, time and location. How high was it above the horizon, and in what direction? What did it look like? How bright was it? What colour was it? How big did it look? Be careful. If you are not an experienced sky watcher, it is easy to confuse “big” with “bright”.
How long did it last? Bright planets just hang in the sky like lanterns. However Iridium flares typically last a few seconds. Was it moving? This is not an easy one to answer. Try this experiment, go outside on a clear night and stare at a star. After a while it seems to be moving, especially if there are clouds. The only check is to assess the position of the object relative to nearby stars and see if that position is changing. Note any details that catch your eye, no matter how trivial. However, just record exactly what you observed. If you want to speculate as to what you could have seen, make sure that is done separately from the report, and AFTER you have the facts written down.
These days we tend to use smart phones as note books and memory holders. Any images or other additional information are always useful, but in no way do they replace written notes, taken down as soon as possible, and promptly reported to local astronomy groups, local observatories or media.
Jupiter is high in the south after dark, moving into the west by midnight. Saturn rises around 11pm. The Moon is currently almost New and will reach First Quarter on the 19th.
Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astro-physical Observatory in Penticton.
ken.tapping@nrc-cnrc.gc.ca.