2 Measuring vitamin D levels is also expensive, costing between $50 and $220 per test in commercial laboratories for patients without insurance. Another challenge is that the level of 25-hydroxy-vitamin D that should be considered normal is unclear.
The closer a planet is to the sun, the shorter the time to complete one revolution is. Mercury, for example, has an orbital period of 88 days while it takes Jupiter about 11.86 years. The period of the Earth's orbit is usually thought to be 365 days as calendars show. However when averaged it is actually about 365.25 days, which requires an extra day on the calendar every four years (causing a leap year). Contradictions within orbit times are probably caused by the ages of the sources.
A year on Earth is obviously 1 year long, since itâs the standard of measurement. But we can break it down further. A year is 365.24 days. Or 8,765 hours, or 526,000 minutes, or 31.6 million seconds. The tricky one is the number of days. Because the earth year doesnât work out to exactly 365 days, we have the leap year. If we didnât, days in the calendar wouldnât match up with the position of the Earth in its orbit.