MADVOX Regolith

Lunar Phases, Position and Orbital Information

   

Important: Linux Experimental Version - I am making Regolith available to Linux as a desktop application. This is experimental at this time. If you encounter any error running this application in Linux please do let me know so I can resolve it - Thank you!

Regolith is a convenient app that approximates several calculations for the position, visibility, phases, eclipses, rising and setting times and other data about the moon. The program is not meant to be an exact representation of all the physics and mechanics that govern the moon; instead, Regolith is an aid to any observer, to quickly look up important data about the moon in a sufficiently accurate manner.

"Sufficiently Accurate" is a direct reference to Jean Meeus. This program was written as an implementation of Astronomical Algorithms, originally developed by Jean Meeus: his incredible work in the field of Computational Astronomy has been the inspiration for many works, including this one. While the calculations performed by Regolith are not meant to emulate NASA's ephemerides, Meeus' algorithms provide sufficient accuracy for the casual observer and amateur astronomer and that is what you will find here.

These are the functions that Regolith can perform:

* Detailed ephemeris of the moon for a given date and time, including observer's coordinate and time location and altitude
* Visualization of the phases of the moon in a calendar-like format with real pictures obtained from NASA's LRO site
* Real-time almanac for any given month (from the years 2000 to 2050) including illuminated fractions
* A century of lunar eclipses, partial, total and penumbral
* A high resolution full moon for panning, scrolling and zooming into features as an observing aid
* Angle and date calculations to help you resolve your location and timing
* All calculations can be scrolled into the past or the future
* All screens link to each other for convenience


To use Regolith you must first establish your location profile (otherwise, all calculations default to midnight - Greenwich) - this is called your "observatory". You may look up your city's coordinated easily by searching google (for instance, "Washington DC coordinates" and simply enter the location angles provided in decimal form (e.g. 53.2366). Also check the box for Daylight Savings Time and enter your time offset from GMT (for instance, in the eastern US this would be 5 hours - no sign needed for positive offsets, use negative sign for negative offsets).

After your profile is set, time of day is controlled by the Ephemeris function thus, if you need to perform a calculation for a specific time, go to the Ephemeris page and change the time there. Upon entering this page the clock is always reset to the exact time on your device, for convenience.

Although we did not include a chart, the Ephemeris page will provide you information about altitude and azimuth for the moon as well as other positional data to help you locate it.

To use Regolith you must first establish your location profile (otherwise, all calculations default to midnight - Greenwich) - this is called your "observatory". You may look up your city's coordinated easily by searching google (for instance, "Washington DC coordinates" and simply enter the location angles provided in decimal form (e.g. 53.2366). Also check the box for Daylight Savings Time and enter your time offset from GMT (for instance, in the eastern US this would be 5 hours - no sign needed for positive offsets, use negative sign for negative offsets).

After your profile is set, time of day is controlled by the Ephemeris function thus, if you need to perform a calculation for a specific time, go to the Ephemeris page and change the time there. Upon entering this page the clock is always reset to the exact time on your device, for convenience.

The information provided by this program does not always match NASA's or [enter-name-here]: For total accuracy, I recommend you use NASA's data or data from other well-known astronomical associations. This program is "sufficiently accurate" but it does not intend to replace those sources at all. This program is designed to help a casual observer or user to quickly obtain information about the moon.

How accurate is the program then?: It is accurate and using Meeus' own words - it is sufficiently accurate - so that when you look at the moon it will match what you see. The accuracy concerns need bother you only if you are intending to do detailed observation work. To find the moon and its phases and mean distances and orbital parameters, this program is accurate!

Some other programs report slightly different phases or times: This program takes into consideration your geographical location as well as your time zone and altitude and thus, it may provide more accurate - if slightly different results, than others that simply report mean data at 0h GMT. For almanacs, this program defaults to midnight UTC. But again, this is "sufficiently accurate", just to dispell any concerns.

The illuminated fraction of the moon differs from the ephemeris page/phase page and the almanac page: this is normal because: the ephemeris and phase pages calculate the phase of the moon for your exact local time. The almanac and the calendar pages calculate the phase for UTC 0 hours which can be a different time or even the next day with regards to the time you have set. So this is normal. Simply know this: when landing on the Ephemeris page or on the Phase page directly from the main menu, the time is defaulted to your local time unless you change it on the Ephemeris page itself. If you access these pages from another page, the time is set by that other page (in the case of the calendar or almanac, this will be midnight UT).

Some times I see more than one [full moon] in a month: Yes, this can happen for two reasons... There is indeed a second moon because the moon cycle is shorter than a regular calendar month or... you are in the almanac page which provides fast approximations. When in the almanac page, consult the illuminated fraction (provided) of the disk which will clear up which phase is the actual one on that month.

What is the range of timing accuracy of this program?: Year 2000 to 2050 (2100 for Eclipse Data). I deliberately limited the calculations to that time frame because this program does not require data beyond the Y2K epoch and to speed up performance on small devices.

What other sites can I refer to for additional information?: In addition to the NASA LRO site provided above, you can visit one of the topmost authorities here at the US Naval Observatory.

Do the default coordinates visible in the Observatory page correspond to a real place?: Yes, they correspond to Huelva, Spain? Why? Because... :)

Roguetoad Studios - This program was produced with the help of Roguetoad Studios who provided images, themes and icons. This program also uses some clipart and icons from Open Clipart. Some script libraries from the Apache Cordova Project. Most special thanks to Jean Meeus whose book - Astronomical Algorithms - provided the inspiration and starting work (for the 5th time since we made a program like this quite a while back!). On that last point, special thanks to Peter Hayes who had entered Meeus' tables into Javascript; for me this program is a rewrite as I have used Meeus' algorithms before but Peter Hayes' periodic elements saved me considerable typing time!! Accurate raw data on Lunar Eclipses was used under permission from NASA's eclipse site.