In one sentence, describe what the following article is about:

If you believe that astrology can predict your future based on your birth date and time, you might have already constructed a star chart or hired someone to do so. If your birth time is based on your mother's memory, if it was rounded to the nearest hour on your birth certificate, or if you have no idea what it is, your star chart may be based on incorrect information. These online calculators below will tell you how likely it is that a given type of star chart, or part of a star chart, is accurate. Enter the number of hours you think your birth time guess could be off by, such as "3" if you only know the general time of day, or "12" if you do not know your birth time. If there is a high chance of your star chart matching the predictions anyway, you may want to skip the arduous process below.  Moon signs for Western astrology or Vedic astrology  Zodiac sign of your ascendant Solar arc Dasha predictions . This star chart doesn't have to have much detail, since it will just be a starting point. If you don't know your birth time at all, make the chart as though you were born at noon. If you know it was between 4:00 and 8:30, make the chart for 6:15. You can hire an astrologer if you do not know how to do this, or learn how to do it yourself. You can also hire an astrologer to "rectify your star chart," and skip the steps below. Write down as many major events in your life that come to mind. You'll need a year, a date, and preferably a time for each one. Traumatic events and accidents are the most useful, but you should also include marriage, divorce, childbirth, change of employment, and other major events. You can use these to see whether the predictions for your current star chart match the events in your life. Use transits, solar arcs, and other astrology techniques to map out predictions based on the "best guess" star chart. Here are some tips on which to use, based on how quickly the astrological bodies move through the chart. Consult an astrology website or astrologer if you do not know how to do this:  Any solar arcs except the Ascendant, Midheaven, and Moon. Transits for Jupiter, Saturn, Uranus, Neptune, Pluto, and the Lunar Nodes. If you are confident of the birthday, add the Sun, Mercury, Venus, and Mars. Different astrologers use different techniques to "rectify" a star chart, but the basic idea is to see whether your life events match the predictions, or to check whether your life events can be explained by a different birth time. Here are a few techniques experienced astrologers use:  Eliminate events that can be explained by natal planetary connections. Look at remaining events, and see whether they are concentrated when celestial bodies arrive at specific degrees. Those degrees could correspond to your Ascendant and Midheaven, if the positions work out. Compare recent outer planet (Jupiter through Pluto) transits to recent life events, to see which house appears to influence you.

Summary:
Find out whether this is necessary. Have a "best guess" star chart made Write down a list of major events. Make predictions based on the star chart. Compare the predictions to your actual life events.