# Emerald Observatory for iPad vs D

The clearest difference is monetization model: D at free against Emerald Observatory for iPad's paid. D also leads on update cadence (every 5 weeks vs every 5 months) and device support (3 vs 1). Emerald Observatory for iPad's advantage is ratings volume (99 vs 1). On price, rating, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 4.9 for Emerald Observatory for iPad against 5.0 for D. That said, the two scores are not equally well evidenced: Emerald Observatory for iPad has 99 ratings behind it against 1, so its average is the more settled of the two.

Emerald Observatory for iPad ships an update every 5 months, D every 5 weeks. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Emerald Observatory for iPad | D |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (99 ratings)](https://appshunter.io/ios/app/emerald-observatory-for-ipad/id364904759/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/d-day-countdown/id1518400866/reviews)** |
| Number of ratings | **99** | 1 |
| Positive reviews | 98.7% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 5 months | **Every 5 weeks** |
| Monetization | Paid | **Free** |
| Size | 19 MB | 7 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | iPad | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [Bjorn Freeman-Benson](https://appshunter.io/developer/1766829089) | [Si-Wan Yoon](https://appshunter.io/developer/1493152910) |

## What reviewers say

### Emerald Observatory for iPad

[App page](https://appshunter.io/ios/app/emerald-observatory-for-ipad/id364904759)

This app provides a comprehensive astronomical display on a single screen, offering detailed information about celestial bodies and timekeeping. It features a heliocentric orrery, rise and set times, twilight information, and moon phase details. Users can navigate through time and set alarms for astronomical events.

**Highlights:** Astronomical information display, Heliocentric orrery, Rise and set times for Sun, Moon, planets, Twilight times, Moon phase and orientation, World map of day/night regions, Eclipse simulator

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none

**What reviewers like**

- ✨ Visually stunning and beautiful design
- 💡 Extremely informative and data-rich
- 👍 Elegant and exquisite user interface
- 🚀 Flawless UX and intuitive design
- 🌟 Unique and nonpareil functionality

**What reviewers complain about**

- ⏳ Last update a year ago
- 🤔 Interface can be tough to decipher initially
- 🔄 Lack of recent updates
- 📱 Not available on iPhone/Apple Watch

**Requested features**

- Port to screen wallpaper
- Large wall clock version
- Apple TV version
- Support for Uranus, Neptune, and Pluto
- iPhone and Apple Watch versions


### D

[App page](https://appshunter.io/ios/app/d-day-countdown/id1518400866)

Easily set and track important dates, such as D-Day. This utility app helps you monitor the remaining time until your specified events.

**Highlights:** Set D-Day, Check remaining time, Event tracking, Simple interface

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support, iPhone Duo support

**In-app purchases:** none


## Frequently asked questions

### Is Emerald Observatory for iPad free?

Emerald Observatory for iPad is free to download, with no in-app purchases.

### Is D free?

D is free to download, with no in-app purchases.

### Which has better reviews, Emerald Observatory for iPad or D?

D is rated higher. Emerald Observatory for iPad averages 4.9 out of 5 from 99 ratings, while D averages 5.0 from 1 ratings.

### Do Emerald Observatory for iPad or D have ads?

Neither Emerald Observatory for iPad nor D shows ads.

### Which is updated more often, Emerald Observatory for iPad or D?

Emerald Observatory for iPad ships an update every 5 months, and D every 5 weeks. Most recently, Emerald Observatory for iPad was updated on November 1, 2026 and D on November 3, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*