About SunClock
|
SunClock was "Rated Top 5% WebApplet" by
JARS."
If you find bugs in this program (or improvements), please
contact me.
Please note that SunClock requires Java 1.1 support and over-exerts
some browsers.
|
Copyright © 1996-1998 Martin Minow. All Rights Reserved.
The SunClock applet displays the current time of day, the phase of the moon, and
a map of the world showing the sunrise and sunset terminator. It also displays
the times of twilight, sunrise and sunset, as well as the age of the moon, the
number of days since the last new moon, and the times of moonrise and moonset.
Look closely at the moon image when you run this applet on July 20, the
anniversary of the first landing on the moon.
You can use the configuration dialog to set the latitude, longitude, and timezone
to a specific location or you can click in the world map to move the observer's
location, however, you may need to use the dialog to set the timezone offset
correctly.
Regrettably, this is a large applet and will take a while to load. Please
Click here for a simpler applet.
- Clicking on the world map will "relocate" the position to this
location. You may need to adjust the timezone using the Option dialog.
- The "Set Options" dialog lets you specify your location and time zone.
It includes a small list of cities and their locations. Please
send me corrections, particularly for timezone names.
- The "About" dialog gives you more information about the program.
Adding SunClock to Your Home Page
You may use SunClock in your personal, non-commercial, home page. In doing
so, you understand that I make no expressed or implied warranty of any kind
and assume no responsibility for errors or omissions. No liability is
assumed for any incidental or consequental damages in connection with
or arising out of the use of the information or program. In particular,
you understand that times of religious observance have not been validated
by competent religious authority.
To add SunClock, add the following HTML to your web page:
<applet
codebase="http://www.vmeng.com/minow/sunclock"
archive=SunClock.zip
code=SunClockApplet.class
width=494
height=440
>
<param name=location value="Your City Name" >
<param name=timezone value="Timezone Name" >
<param name=latitude value="Latitude Value" >
<param name=longitude value="Longitude Value" >
<param name=bgcolor value="#FFFFFF" >
The SunClock Applet is displayed here if your browser
supports Java.
SunClock requires Java 1.1 browser support.
</applet>
The parameters are defined as follows:
location
- Your city name. This is only for reference.
timezone
- Your timezone. This is one of the pre-defined named
timezones, such as "EST" or "GMT".
latitude
- Your location's latitude. See format definition below.
longitude
- Your location's longitude. See format definition below.
bgcolor
- The display background color. This should be a light
color that fits into your page's overall layout. It
is specified as a hexadecimal string, such as "#CCCCFF".
Latitude and longitude may be specified either as a signed decimal
value: "-90.0" to "+90.0" for latitude and "-180.0" to "+180.0"
for longitude; where "+" designates North or East and "-" designates
South or West. The values may also be specified in degrees and minutes
using the format "DD:MM", and you may also use "N", "S", "E", and "W"
to designate a direction. For example, the following values all designate
San Francisco, California, at latitude 37&174;48 North, 122&174;24 West:
name=latitude value=37.8
name=latitude value=N37:48
name=longitude value=-122.4
name=longitude value="E122:24
SunClock uses the times of sunrise and sunset to compute times of religious
observation and obligation for Judiasm and Islam. You are, however, strongly
advised to seek religious advice for guidance in interpreting the results of
this software. This is especially true for times at high latitudes when the
sun may not set or rise throughout the day.
- Sunrise and sunset are defined as the time when the sun is 0°50' below the
horizon.
- Civil twilight (default twilight) is defined as the time when the sun is 6°
below the horizon.
- Nautical twilight is defined as the time when the sun is 12° below the horizon.
- Astronomical twilight is defined as the time when the sun is 18° below the horizon.
These values assume that the observer is at the horizon. If the horizon is significantly
above or below the observer, the altitude must be changed accordingly. This will require
slight modification to the program, as noted in Constants.java.
The computation of Jewish religious observance were taken from Andrew H. Shooman's
sunrise_prg.c, 26 January 1992. This program computes the following times.
|
Sun position
|
Explanation
|
|
-15°
|
Morning Alot HaShachar: the earliest time to begin Shacharit.
|
|
-12°40'
|
Taalit v'Tfilin: the time to wear Tallis and Tefillin.
|
|
Three hours after sunrise.
|
Sof Z'man Kriat Sh'ma.
|
|
Midday.
|
The mid-point between sunrise and sunset.
|
|
-9°
|
The end of Sabbath or holiday observation. Derived from
Rav Yehuda's Tzeit ha-Kochavim from Shabbat 24b, 35a.
|
The computation of Muslim religious observance were taken from "Astronomy of Islamic
Times," by Mohammad Ilyas, 1988. ISBN 0-7201-1983-9. If you are interested
in a calendar of Muslim prayer times, you may find the
Muslim Prayer Time home
page useful. Also,
Waleed A. Muhanna provides a web page with
programs for generating Islamic (Hijri) calendars, computing payer time
schedules, and for determining the direction of the Qiblah. This program computes
the following times.
|
Sun position
|
Explanation
|
|
-18°
|
Fajr. Dawn: the beginning of astronomical twilight and end of night.
Waleed A. Muhanna's
web page notes that -15° is sometimes used in the United States.
|
|
-0°50'
|
Shurooq. Sunrise.
|
|
Mid-day
|
Zhuhr. The mid-point between sunrise and sunset. It may be more correct to
use the time of the sun's highest point.
|
|
Asr (Shafi).Defined as 90° - arccotangent(1 + cotangent(An))
where An = 90° - the sun's zenith angle at noon.
|
|
Asr (Hanafi).Defined as 90° - arccotangent(2 + cotangent(An))
where An = 90° - the sun's zenith angle at noon.
|
|
-0°50'
|
Maghrib. Sunset.
|
|
-18°
|
Isha. Night: the end of astronomical twilight and beginning of night.
|
Click here for more information and links to all source code.
Copyright © 1996-1998
Martin Minow. All Rights Reserved.
World map copyright © 1992-97 Apple Computer Inc. All Rights Reserved.
Used by permission.
The moon image was adapted from a photograph by
Michael Myers, and is
used by permission.
Permission to use, copy, modify, and redistribute this software and its
documentation for personal, non-commercial use is hereby granted provided that
this copyright notice and appropriate documentation appears in all copies. This
software may not be distributed for fee or as part of commercial, "shareware,"
and/or not-for-profit endevors including, but not limited to, CD-ROM collections,
online databases, and subscription services without specific license. The
author makes no expressed or implied warranty of any kind and assumes no
responsibility for errors or omissions. No liability is assumed for any incidental
or consequental damages in connection with or arising out of the use of the
information or program.
Return to my home page.