Can You See Stars Moving in the Sky?

Throughout the night, many things glimmer brightly in the sky. Some are fixed except for perhaps a slight twinkle, while others seem like stars until they shoot across the night. What are these fast-moving things � falling stars, or something else entirely? And are falling stars really a star?

The stars do move across the sky over the course of a night as the earth rotates, but it is nearly impossible to actually notice this motion except near the horizon. Think of the Sun, the brightest star in our sky � you can notice that it moves throughout the day, but except perhaps near sunset or sunrise it's nearly impossible to see it moving. It simply goes too slowly. Long-exposure photography reveals the circles drawn by each star due to the earth's rotation, but it's safe to say that the movement of the stars is far from quick according to our point of view.

So when you see a bright star-like object moving across the sky, what is it, then?

There are multiple possibilities, of course. Aircraft moving overhead, especially those at a distance or only showing non-blinking white lights, can easily turn into a single point of light against the black backdrop of the night sky. These tend to move with a fairly fast and steady pace. This is one of the most common 'starlike' moving objects.

If you see a bright moving star, often brighter than Venus, against the sky during the day, know that while it's not a star you should still count yourself lucky � you've had a fairly rare naked-eye sighting of a manmade satellite. Satellites sometimes catch the light from their sun on their panels and become visible from the ground as brief-lived, incredibly bright stars.

Flares or small rockets launched at a fair distance can be visible as something like a star, moving briefly and vertically across the sky. These are somewhat less common in the days of personal GPS systems and firework safety, but still a possibility on occasion.

Last but certainly not least, there are the true "falling stars" � meteors. When a meteoroid, a small piece of space debris, enters the atmosphere, the heat and friction of the air causes the meteoroid to heat dramatically and glow strongly enough to be seen from the ground. The visible flash of light and streak is known as a meteor. While it may not be a star falling from the heavens, the sight of a meteor can still be quite beautiful and dramatic � especially during meteor showers, when hundreds of meteoroids enter the atmosphere and streak across our skies.

So, is what you're seeing move across the sky a star? No, but it might well be a satellite high above the earth, a piece of debris from space, or just a fireworks show � which are all still very interesting things indeed.

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