Controls

• Drag one finger horizontally to change the view longitude, vertically to change the latitude.


• Drag two fingers to change the view inclination.


• Pinch or expand two fingers to get closer or farther away.


• While the globe is spinning, tap anywhere on the globe to stop movement.


• Tap on any blank area to show or hide the controls and labels.


• Tap the Time/Illumination button to switch between time or illumination mode.


• In time mode: tap on the time zone label to toggle time readout between Earth time and Mars Rover time. Tap the date and time fields and use the sliders to change the current display time.


• In illumination mode: use the slider to shift the illumination left or right.


• Tap the feature type label to toggle between display modes showing Spacecraft, Terrain Features, Highlights, Albedo Features, and People.


• Tap on any label to see information about that feature.


• Tap the arrow buttons to go to the next or previous feature.


• Tap the map type button to switch between normal color mode and elevation map mode.


• Tap the options button to display additional options.

Map Types: Color and Elevation

In Mars Globe you can switch between two different views of the surface, a natural color view and a false-color elevation view. Tapping the map type button switches between the two. The button displays "C" for Color when in Color mode, and "E" for elevation.

The "natural color" view attempts to portray Mars as it would appear to a human viewing from above the planet. Please note, however, that the color is an approximation.

The elevation view shows the surface in a spectrum of colors corresponding to the height of the terrain, relative to the standard Mars reference altitude. ("Sea level" is used as a reference on Earth, but Mars does not have an ocean, at least not today.) The colors start at purple for the lowest elevations (for example, Hellas Planitia), and traverse the spectrum up to red for high terrains (for example, the Tharsis area), and then transition to a pastel spectrum to depict the highest elevations, which are found only on Mars' massive volcanoes. The color scheme used to show elevation is very similar (but not identical) to this one used by NASA.

By switching between the color and elevation views, you can compare what Mars looks like to the actual lay of the land. Lighting effects apply to both the color and elevation views, so adjust the lighting to find the most advantageous view of the terrain you're looking at.

Labels, Information, and Links

Tapping the label mode button at the bottom of the screen switches between label modes, which display labels over different features of the planet. The label modes are:

• Spacecraft: Successful landers and rovers on Mars (and a few unsuccessful ones) are displayed with crosshair labels.


• Terrain: Terrain features of Mars are displayed. This is the primary option, which displays the most information about the surface.


• Highlights: Selected highlights of terrain features are displayed. You can navigate from one Highlight feature to the next using the arrow buttons, to create a guided tour.


• Albedo: Albedo features are the variations in brightness of areas of the planet. Albedo features have been observed on Mars since the early days of the telescope, but they tend to represent patterns of dust on the surface, rather than actual properties of the terrain. As such, they are nebulous and poorly defined, often changing over a period of years. Many of the terrain features of Mars are named after albedo features, as the albedo features were observed first, distantly, from Earth, while almost all actual terrain features were discovered by spacecraft observing at close range.


• People: Many of the craters of Mars have been named after historical scientists or other distinguished humans, particularly those who have contributed to the understanding of the planets; this mode displays labels only for those features. People features are sorted in order by birth date, so that you may navigate through a partial history of human discovery.


• Height: No labels are displayed in this mode; instead, the label mode button displays the viewer's elevation above the planet surface. (For technically-oriented people: the distance displayed is actually the distance above the MOLA reference radius of Mars, 3,396 km from the center of the planet. The horizontal field of view in the app is 45 degrees.)

Tapping on any label brings up an information window displaying some information about that feature. Drag a finger vertically across this information window to scroll up or down, and tap on the circular "X" close button to dismiss it.

Many feature descriptions contain links to resources on the Internet that can provide even more information or additional images. Tapping on these links brings up a Web viewer and connects to the Internet. Please note that information on Wikipedia is provided by volunteers, and may be of varying quality, particularly as articles on Martian surface features generally don't receive much attention from editors. Where available, links to NASA or European Space Agency (ESA) articles on the terrain features are preferred.

Sound

The Sound switch in the Options menu controls whether clicks are made when controls are pressed. The sound effects will not interfere with any music you choose to play from your own music collection. Please note that sound effects will not play if your iPhone's "silent mode" switch is on.

Remember Position

The Remember Position switch in the Options menu controls whether your current viewing position is remembered when you leave the app. The default is "Off"; with this setting, you always face the sun-illuminated side of the globe when the app starts.