Ramadan 2010 will either take place August 11, or August 12, depending on where you live. As of today, the majority of the Muslim world has sighted the moon and decided that Ramadan is tomorrow, Wednesday, August 11.
The reason for this uncertainty of the date is that the Islamic Calendar is a lunar one, whereas the Gregorian calendar is a solar calendar. So in order to find out the date that the new month begins, the moon must be sighted as a crescent moon to signify the beginning of the new month.
The Lunar year is also 11 days shorted than the Solar year, so Ramadan always comes 10-12 days earlier than the year before. How many exact days earlier depends on how many days are in all the other months of the Lunar year. This also means that around every 33 Gregorian years that pass, you are actually one year older (34 years), by Islamic years.
So what if it's a cloudy night, and you cannot see the moon properly? Or what if you live in the North Pole where it's six months of daylight, and six months of dark? The majority of the scholars agree that as long as the moon is sighted in a country that you share a part of the night with, then you can use their moon sighting to signal the start of Ramadan. This fatwa (ruling) is also used to calculate the beginning and end of all other Islamic months.
Some North American Muslims prefer to sight the moon themselves, in their own country, whereas others are fine with starting Ramadan if the moon has been sighted in their country of origin. Therefore, it isn't uncommon to find some Muslims, in the same city, starting Ramadan and Eid-Ul-Fitr on different days than others. Both opinions are correct.
Many cities now try to come to an agreement with all the Islamic centers and organizations so that all the Muslims in the same city celebrate Ramadan and Eid-Ul-Fitr at the same time.
If you would like to wish someone well in Ramadan, the proper greeting is "Ramadan Kareem" (May your Ramadan be full of generosity) or "Ramadan Mubarak" (May you have a blessed Ramadan).
The months of the Islamic Calendar are as follows:
Rabee' Al-Awal (Rabee' the first)
Rabee' Al-Thanee (Rabee' the second)
Jumaad Al-Ulaa (Jumaad the first)
Jumaad Al-Thanee (Jumaad the second)
I will be posting more about Ramadan in the upcoming days, so stay tuned!