Earth revolves around its own axis in approximately 23 hours 56 minutes 4 seconds. If we measure the length of a day by 24 hours we hour saving 180+56=234 seconds a day. In a year that is 234 * 365 = 85, 410 seconds. In 4 years that is 341,640 seconds. Now a say has 86400 seconds, so we are the end of 4 year we have 341,640/86400 = 3.95 days. But we add 1 day to February after 4 years. Why is this?
In: 2
The earth is actually rotating a little bit faster than it is revolving around the sun, so each day on Earth is actually slightly shorter than 24 hours. This means that the extra 3 minutes and 56 seconds of rotation are added up over the course of a year and, by the end of the year, the days have added up to 3 days. So, the 3 days are simply the extra time it takes for the earth to complete one full rotation around its own axis.
23 hour 56 minutes and 4 seconds is what’s called a sidereal day. The amount of time it takes for the Earth to rotate 360°. This is different from a solar day.
A solar day is slightly longer because while the Earth is rotating on its axis, the Earth is also revolving around the Sun. Since this is happening, the Earth has to rotate slightly further for the Sun to be directly above the same point on the Earth.
A mean solar day is 24 hours because it’s the average amount of time it takes for the Sun to reach same spot in the sky. Since the Earth’s orbit isn’t a perfect circle (it’s an ellipse) the distance the Earth travels each day around the sun is different. The Earth is closest to the sun in January and therefore moving faster, and slightly further away in July, and moving slower (note: this is not the phenomenon that causes seasons, this is different) so if you measure a solar day in January, it will be slightly longer than 24 hours, if you measure one in July, it will be slightly less than 24 hours. If you measure every day of the year and average them together, you get exactly 24 hours.
Short answer: to account for the fact a day refers to the time it takes the sun to be “above” us each time. And we are circling the sun so it takes more than one rotation to have the sun be in the same spot relative to the earth.
Long answer: Think about the earth being at the end of the hour hand on a clock and the sun in the middle of the clock.
Jan 1 the hour hand is at 12, each day the hour hand moves about 2 minutes around the clock face and in 365 days it’s back to 12.
Now in ancient times we didn’t know we were on the the hour hand moving. We thought we were at the center of the clock and the sun was at the end of the hour hand and went all the way around us in a regular amount of time. We silly monkey offspring defined this as “24 hours” and “1 day”.
Eventually we learned the truth. That we are spinning at the end of the hour hand and the sun is the center of the clock. But we still define “a day” as “24 hours” and the length of time it takes for the sun to appear “above” us everyday. But for this to happen the Earth has to spin 360 degrees + 360/365 degrees to still end up facing the sun every “day”.
Short answer: to account for the fact a day refers to the time it takes the sun to be “above” us each time. And we are circling the sun so it takes more than one rotation to have the sun be in the same spot relative to the earth.
Long answer: Think about the earth being at the end of the hour hand on a clock and the sun in the middle of the clock.
Jan 1 the hour hand is at 12, each day the hour hand moves about 2 minutes around the clock face and in 365 days it’s back to 12.
Now in ancient times we didn’t know we were on the the hour hand moving. We thought we were at the center of the clock and the sun was at the end of the hour hand and went all the way around us in a regular amount of time. We silly monkey offspring defined this as “24 hours” and “1 day”.
Eventually we learned the truth. That we are spinning at the end of the hour hand and the sun is the center of the clock. But we still define “a day” as “24 hours” and the length of time it takes for the sun to appear “above” us everyday. But for this to happen the Earth has to spin 360 degrees + 360/365 degrees to still end up facing the sun every “day”.
Short answer: to account for the fact a day refers to the time it takes the sun to be “above” us each time. And we are circling the sun so it takes more than one rotation to have the sun be in the same spot relative to the earth.
Long answer: Think about the earth being at the end of the hour hand on a clock and the sun in the middle of the clock.
Jan 1 the hour hand is at 12, each day the hour hand moves about 2 minutes around the clock face and in 365 days it’s back to 12.
Now in ancient times we didn’t know we were on the the hour hand moving. We thought we were at the center of the clock and the sun was at the end of the hour hand and went all the way around us in a regular amount of time. We silly monkey offspring defined this as “24 hours” and “1 day”.
Eventually we learned the truth. That we are spinning at the end of the hour hand and the sun is the center of the clock. But we still define “a day” as “24 hours” and the length of time it takes for the sun to appear “above” us everyday. But for this to happen the Earth has to spin 360 degrees + 360/365 degrees to still end up facing the sun every “day”.
23 hour 56 minutes and 4 seconds is what’s called a sidereal day. The amount of time it takes for the Earth to rotate 360°. This is different from a solar day.
A solar day is slightly longer because while the Earth is rotating on its axis, the Earth is also revolving around the Sun. Since this is happening, the Earth has to rotate slightly further for the Sun to be directly above the same point on the Earth.
A mean solar day is 24 hours because it’s the average amount of time it takes for the Sun to reach same spot in the sky. Since the Earth’s orbit isn’t a perfect circle (it’s an ellipse) the distance the Earth travels each day around the sun is different. The Earth is closest to the sun in January and therefore moving faster, and slightly further away in July, and moving slower (note: this is not the phenomenon that causes seasons, this is different) so if you measure a solar day in January, it will be slightly longer than 24 hours, if you measure one in July, it will be slightly less than 24 hours. If you measure every day of the year and average them together, you get exactly 24 hours.
23 hour 56 minutes and 4 seconds is what’s called a sidereal day. The amount of time it takes for the Earth to rotate 360°. This is different from a solar day.
A solar day is slightly longer because while the Earth is rotating on its axis, the Earth is also revolving around the Sun. Since this is happening, the Earth has to rotate slightly further for the Sun to be directly above the same point on the Earth.
A mean solar day is 24 hours because it’s the average amount of time it takes for the Sun to reach same spot in the sky. Since the Earth’s orbit isn’t a perfect circle (it’s an ellipse) the distance the Earth travels each day around the sun is different. The Earth is closest to the sun in January and therefore moving faster, and slightly further away in July, and moving slower (note: this is not the phenomenon that causes seasons, this is different) so if you measure a solar day in January, it will be slightly longer than 24 hours, if you measure one in July, it will be slightly less than 24 hours. If you measure every day of the year and average them together, you get exactly 24 hours.
Latest Answers