I saw a bright light just after sunset or just before sunrise. Is it a satellite?
This question has been asked many times during our public observations. The answer is no. It’s Venus! Many may have seen Venus in the western sky just after sunset and in the eastern sky just before sunrise. The confusion may have cause by the brightness of Venus. Other than the Moon (not counting the Sun), Venus is the second brightest object in the sky. Believe it or not, if you go to a very dark area, you may even seen your shadow cast by the light from Venus.
Apart from being bright, it also appeared not to move. But it does move. Within a couple of hours after sunset, it will go below the horizon. Or if it appears in the morning sky, you can follow it rise until it is too bright to be seen. This motion is mostly cause by the rotation of our earth on its axis. The same motion caused the stars to rise and set.
So, what about satellites? How do I know if what I see is a satellite? When is the best time to see them?
Well, most satellites are quite dim, much dimmer than Venus. The brighter ones are the International Space Station (ISS) and the Iridium satellites. Sometimes, when the space shuttle is in orbit, you can see it too. I will usually keep an eye for them if they are to pass over Malaysia at a suitable time. A suitable time would be a few hours after sunset and a few hours before sunrise. (Hey, that’s the ideal time to see Venus too, no wonder people confused Venus for satellites!). If you want to know when a satellite passes over Malaysian sky, you can log into www.heavens-above.com. Enter your coordinate, if you know them. Or just choose the city near to you. Every night, you should be able to see a few, although not bright.
When a satellite does go across the sky, it will appear like a moving star. It will take about a couple of minutes to transit the sky. There are no specific directions. Most will be from North to South, or South to North or anywhere in between. You may think that you are looking at a plane, but if you observe carefully, there will be no blinking lights like the plane. It will also appear to be a single point of light. Plane may have a few.
One exception is the Iridium satellites. There are more than 60 of these satellites orbiting the earth. They are used for telecommunication, but are now decommission.
The interesting things about these satellites are that they can be very bright. They also don’t appear to go across the whole sky. When they first appear, they are dim. As they move, they seems to become brighter and brighter. Then suddenly, the intensity drops until they disappear altogether. Look kind of like seeing a UFO!!! Check out their flyby dates from heavens-above webpage to see these satellites and impress your friends.
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