ball Terra

The world in the palm of your hand

July, 2016. Version 4.6



Terra gives you quick access to astronomical information, weather forecasts, earthquake reports, time zones and factual information about any part of the Earth. It presents a 3D globe which you can spin to see any point on Earth. You can also move forward and back in time.

New in version 4.6:

The daytime Earth image is now chosen from twelve, one for each month of the year. NASA did these to show the seasonal changes over a year's time. If you prefer the single Earth image, go to the settings and turn off the switch called "Use monthly images".

New in version 4.5:

iOS9 compatible


You can see:

  • your current location
  • the altitude and azimuth of the Sun and Moon at any location on Earth and at any date and time
  • the rising and setting times for Sun and Moon, at any location and date
  • the illumination of the Earth by the Sun at any time, the Terminator line and the twilights (civil, nautical and astronomical)
  • the length of the day for any location and date
  • the phase of the Moon and its appearance to the observer4
  • the shortest distance and compass bearing between any two locations
  • sidereal time, Greenwich and local

Time Zones
Terra shows a globe with a political map of the Earth with more than 250 locations highlighted. Tapping a button will center the globe on a location and show its local time, correct for standard or daylight.

Terra will link to the Weather Underground web site and show the current conditions and forecast for any location.

Terra will download the latest earthquake report from the USGS and display the quakes on the globe. You can jump to the USGS web site for more detailed information about any quake.

Terra will link to the CIA World Factbook web site for almost every country.

It will be useful to:

  • travelers,
  • business people,
  • photographers, cinematographers,
  • students,
  • architects,
  • gardeners, landscapers,
  • amateur astronomers,
  • radio hams,
  • those concerned with solar energy.


More than 250 locations are outlined in black. The nearest to the center is shown by a blinking black dot. Terra will show you the local time at any of these locations. You can jump to the iPhone Maps application for a more detailed view of any location.


Terra shows

  • the Earth as lit by the Sun
  • the position of the Sun
  • the twilight zones
  • the subsolar and sublunar points
  • the next sunrise and sunset
  • the length of the day
  • the observer's location
  • the current time
  • the approximate color of the sky


Terra shows:

  • the location and phase of the Moon
  • the next moonrise and moonset
  • the approximate color of the sky
  • the observer's location
  • the current time

Terra will show the current sidereal time at Greenwich and at the central point.

Terra shows:

all earthquakes within the last week of magnitude 2.5 or greater. You can set the lower limit on magnitude. Each is shown by a square. The size represents the magnitude, the color indicates how recently it occured. The nearest to the center will blink. Its location and magnitude are shown in the bar below. You can jump to the USGS web site or to the iOS Maps application for a more details about the quake and the location.

© Copyright 2013 David A. Rowland
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