Do the stars move?
Tuesday, September 12 The stars may look fixed, but that is an illusion of time and space. They are so far away the human eye alone cannot detect their motions on the sky. ASK THE ASTRONOMER Have a question for columnist Jeff Kanipe? Now you can Ask the Astronomer. Their apparent motion, measured over a year’s time, is referred to by astronomers as annual proper motion. Because they are nearby, stars nearest the sun exhibit the greatest proper motion, while those at more remote distances appear virtually fixed. The amount of positional change is so small it is expressed in the angular value of arcseconds. One arcsecond is roughly equal to the size of a quarter seen from a distance of about 3 miles (4.8 kilometers). Proper motion is a combination of the star’s true direction and velocity in space, as well as its motion relative to our solar system. In our part of the Milky Way, stars move at an average velocity of about 15 miles (24 kilometers) per second. The sun, too, moves through sp
Yes and no. The stars in the Milky Way galaxy are all moving in relation to the center of the galaxy; they rotate around the galactic center in very much the same way the Earth rotates around the Sun. The earth and the Sun, for that matter, both rotate around the galactic center, too. This is why the stars do not appear to move from our point of view; both the Earth and the stars are rotating around the galactic center in the same direction; hence, from our perspective, the stars do not move. We can see the stars move across the sky each night, however. The visible motion of the stars is due to the motion of the Earth; the stars remain in the same position relative to each other, but seem to move across our sky because the Earth itself is moving around the Sun.
As we know, stars do not move. Stars are like our sun. They are stationary and do not move, but planets and moons do move. They orbit stars. Anyhow, why it looks like that stars move? As you watch the sky in early night, it looks different than later at night. Stars change their position as the night goes on. They start rising in early evening, reach the highest position after midnight and finally go below the horizon in early morning. Only the circumpolar stars do not go below horizon, but also their position in our night sky changes. As an example, take a look at my previous post: Planet Saturn in Early February Observed from Northern Hemisphere. The obvious reason for this phenomenon is that our planet move. The Earth circulates, and that’s why we see the sun and other stars changing their location in the sky. Because of this we have days and night. In addition to circulation, our planet is on move. We orbit the Sun and because of this we have winters and summers. Based on our conti
