Why Do Stars Appear to Move in a Four-Year Cycle?

Thread starter shirin
Start date Sep 11, 2013
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Movement Stars

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Stars appear to move in a four-year cycle due to the difference between the sidereal day and the solar day, resulting in a cumulative effect over time. Each year, stars complete approximately 366.25 rotations, causing their positions to shift slightly. Observations of stars like Sirius show that they rise higher in the sky for three consecutive years before returning to their original position in the fourth year. This phenomenon is influenced by the leap year, which adds an extra day to the calendar and affects the timing of celestial observations. Understanding this cycle enhances the appreciation of star movements in relation to Earth's orbit.

Sep 11, 2013

shirin

Hello everybody!
I read that because of about 4 min difference between sidereal day and solar day, at the end of a year each star has rotated 366.25 times(apparently). I looked up in software such as Starrynight, the position of for example Sirius at 1 September of 2013, 2014, 2015 and so on. I recognized that it goes up for 3 successive years and returns back to its first position at forth year. Why is it so?

Thanks

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Sep 11, 2013

Drakkith

Mentor

Leap year?

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