Emerald Observatory for iPad is Drop Dead Gorgeous

There are many reasons for customers who are not even amateur astronomers to own Emerald Observatory: obtain times for twilight, sunrise, sunset, when the various planets rise and set and their positions in the sky, the position of the terminator on the Earth, the phase of the moon, and Greenwich/UTC time. The app is gorgeous and showcases the iPad even if just used as a clock.

Emerald Observatory is a one page app that packs a lot into one beautifully designed display. (You can use either portrait or landscape mode.) Some of the data is obvious, such as the Time Zone and local time, some will require some study of the documentation, some is more relevant to an amateur astronomer’s observatory, such as Sidereal Time, and maybe one or two is just a waste of space, such as the Leap Year indicator.

Emerald Observatory

Emerald Observatory for iPad

At the bottom of the display is the classic “i” icon that invites the user to get more information. However, it is very important to note that the info page is just a summary and doesn’t cover every display in detail. To get complete information on deciphering the display, go to the developer’s website.

Some of the displays have technical meanings that not many casual users will appreciate, such as the Solar Time (the local hour angle of the sun) and the Sidereal Time, used by amateur astronomers in the old days, before computer driven clock drives, to locate objects in the sky.

Other items that may be of more interest are the rise and set times of the planets, local sunrise and sunset times as well as the times of civil, nautical and astronomical twilight. For example, some local driving regulations dictate when you must have your car lights on as function of not sunrise/sunset but civil twilight. That’s a good time to know. Also, if someone claims to have seen Venus in the night sky at midnight, a quick glance at Emerald Observatory could show that, in fact, Venus has long since set. Knowledge is power.

I didn’t find the Leap Year indicator to be very well designed. I would have preferred a moving tape indicator with years, one that could be swiped, that would show which years are leap years in red. As it is, the Leap Year indicator is not too useful.


Having a degree in astrophysics myself, my first thought was to check the accuracy of the display.

  • I tested the sunrise/sunset/twilight times against NavClock.
  • I tested the planetary rise and set times against StarWalk.
  • I tested the orrery (positions of the planets) against an orrery on the Web.

Everything checked out in a sampling of data, so I am satisfied that the developer got his math (and lookups) correct, based on my geographic location at least.

The Really Cool Part

Emerald Observatory is so great looking, you’ll want to show it off to your friends considering an iPad. The sweep second hand, while nothing out of the ordinary, seems magical and mesmerizing on this display. Everything is just a pleasure to look at. Of course, getting the answers right, for a highly technical, astronomical app, is just as important.

In using the app, I almost feel like Geordi La Forge in Star Trek: TNG, pulling out a small notepad and seeing something so cool, so visual, so technical that it’s hard to believe it’s real. I predict we’ll see this iPad showcase app displayed in a SciFi movie or TV show in the near future. It still looks like it’s from the future, just standing still and looking beautiful.

Emerald Observatory from Emerald Sequoia, LLC requires an iPad, iOS 3.2 or later, and is an absolute steal for US$0.99.