The calendar now almost universally in use is the Gregorian calendar introduced in 1582
One was a lunar calendar based on the phases of the moon. Priests used this calendar to determine religious days and lucky days. The other was a solar calendar,based on the movement of the sun. It's similar to the calendar we use today
The Hebrew calendar is a lunisolar calendar. The months are 28-29 days based on the lunar cycle, but the leap year system is based on the solar cycle. The lunar year is 354 days, but every few years, a leap month is added to keep the months in the same seasons.
It, too, has 365 days and is based on seasons.
The classical Roman calendar was originally lunar, but later developed into a similar system to the modern one (in fact it was a precursor to the current Julian calendar) using months of either 30 or 31 days.
The Islamic calendar is based on the movement of the Moon, not the sun. It is called the Lunar Calendar. It has 354/355 days in a year.
28 days. That is how many days there are in the Islamic calendar, which is based on the phases of the moon.
No, the Jewish year has 365.25 days, just like the Gregorian, but the calendar is calculated differently. The Gregorian calendar is Solar, meaning it's based on the Sun; the Jewish calendar is Lunisolar, meaning its based on the Moon, but periodically corrected to match the Sun. By contrast, the Islamic calendar is Lunar and has only 354 days in a year.
Ramadan follows the lunar calendar and it moves up 13 days each year based on the moon's position.
Seven days, the same as the current calendar system.
The Roman Calendar has 10 months in its system. Among these ten months, there were 304 days. This has been expanded on to 12 months and 365 days, which is still used today.
A lightyear
The metric system. (cenimeters, meters, milimeters)