APT Darkness Clock vs SkySafari 7 Plus
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
APT Darkness Clock
This app calculates the optimal times for deep sky astrophotography and observation based on your location and night sky conditions. It determines the duration and start/end times of ideal darkness, excluding twilight and moonlight.
- Calculates Deep Sky Darkness Time (DSD Time)
- Determines start and end times for DSD Time
- Calculates DSD Time duration
- Supports current location
- Allows storing up to three observing sites
- Free and ad-free
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APT Darkness Clock (APT DC) is a free app without ads, that calculates the suitable time for deep sky astrophotography or observing in selected night and location. It is a small sub-set of a full featured desktop application named APT - Astro Photography Tool. APT is like Swiss army knife for your astro imaging sessions. No matter what are imaging with - Canon EOS, Nikon, CCD or CMOS astro camera, APT has the right tool for planning, collimating, aligning, focusing, framing, plate-solving, controlling, imaging, synchronizing, scheduling, analyzing, monitoring and more. You can find additional information about APT at www.astroplace.net. To image or observe a faint deep sky objects is needed to use the darkest time of the night. This is the time between the evening astro twilight end, the morning astro twilight beginning and when the Moon is below the horizon. In APT that time is named DSD Time - Deep Sky Darkness Time. The purpose of APT DC is to calculate what is the DSD Time duration and when this time starts/ends for selected night and location. It is possible to use the current location or one of three other stored observing sites. For suggestions and support related to APT DC, use the dedicated section of the APT Forum at - http://aptforum.com/phpbb/viewforum.php?f=26
SkySafari 7 Plus
Explore the cosmos with a powerful space simulator and telescope control. Discover astronomical events, track celestial objects, and plan your stargazing sessions with real-time data and historical simulations.
- Full-featured space simulator
- Telescope control (ASCOM Alpaca, INDI)
- Events Finder for astronomical occurrences
- Real-time user observation tracking (OneSky)
- Guided stargazing sessions (SkyCast)
- Observation planning and recording tools
- Home and Lock Screen widgets
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SkySafari 7 Plus goes beyond most basic stargazing apps by providing you with a full-featured space simulator with telescope control. If you are looking to dive deeper into astronomy, start your journey with the #1 recommend app for amateur astronomers since 2009. Note that there is no discount upgrade path from SkySafari 7 Plus to SkySafari 7 Pro. Choose carefully! Here's what’s new in version 7: + Complete support for iOS 15 and iPhone 13. Version 7 brings a new and immersive stargazing experience. + Events Finder - go to the new Events section to unlock a powerful search engine that finds astronomical events visible tonight and far into the future. The finder dynamically generates a listing of moon phases, eclipses, planetary moon events, meteor showers and planetary phenomenon such as conjunctions, elongations and oppositions. + Notifications - the notifications section has been completely revamped to allow you to customize and manage which events trigger an alert notification on your device. + Telescope Support - telescope control is at the heart of SkySafari. Version 7 takes a giant leap forward by supporting ASCOM Alpaca and INDI. These next generation control protocols allow you to effortlessly connect to hundreds of compatible astronomical devices. + OneSky - allows you to see what other users are observing, in real time. This feature highlights objects in the sky chart and indicates with a number how many users are observing a particular object. + SkyCast - allows you to guide a friend or group around the night sky through their own copy of SkySafari. After initiating SkyCast, you can generate a link and conveniently share it with other SkySafari users via text message, apps or social media accounts. + Sky Tonight - jump to the new Tonight section to see what’s visible in your sky tonight. Expanded information has been designed to help plan your night and includes Moon & Sun info, calendar curations, events and the best positioned deep sky and solar system objects. + Improved Observation Tools - SkySafari is the perfect tool to help you plan, record and organize your observations. New workflows make it easier to add, search, filter and sort data. + Home Screen and Lock Screen Widgets keep your favorite astro information at your fingertips. The Small Touches: + You can now edit the Jupiter GRS Longitude Value in the Settings. + Better Moon Age calculation. + New grid & reference options allow you to display Solstice and Equinox markers, Orbit Node markers for all solar system objects, and tick marks and labels for the Ecliptic, Meridian, and Equator reference lines. + Previous In-app Purchases are Now Free - this includes the H-R diagram and 3D Galaxy view. Enjoy. + Many more. If you haven't used SkySafari 7 Plus before, here's what you can do with it: + Hold your device up, and SkySafari 7 Plus will find comets, stars, constellations, planets, and more! + Simulate the night sky up to 10,000 years in the past or future! Animate meteor showers, conjunctions, eclipses, and other celestial events. + Learn the history, mythology, and science of astronomy! Browse over 1500 object descriptions and astronomical images. Stay up-to-date with the Calendar for all major sky events every day! + Control your telescope, log and plan your observations. + Night Vision – Preserve your eyesight after dark. + Orbit Mode. Leave the Earth’s surface behind, and fly through our solar system. + Time Flow – Follow the motion of sky objects as days, months, and years are compressed into a few seconds. + Advanced Search – Find objects using properties other than their name. + Much more! For even more features, and a gigantic database aimed at the most dedicated amateur or professional astronomer, check out SkySafari 7 Pro! https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is review sentiment: APT Darkness Clock at 100% against SkySafari 7 Plus's 46%. APT Darkness Clock also leads on price (Free vs $9.99) and in-app purchases (none vs 3). SkySafari 7 Plus's advantage is ratings volume (1.7K vs 4) and chart position (#170 vs unranked). On ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
APT Darkness Clock is free to download; SkySafari 7 Plus costs $9.99 up front. SkySafari 7 Plus sells 3 in-app purchases, starting at $4.99 per month. APT Darkness Clock asks for nothing beyond the download.
APT Darkness Clock holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: SkySafari 7 Plus has 1.7K ratings behind it against 4, so its average is the more settled of the two. Written reviews point the same way: 100% of APT Darkness Clock's written reviews are positive against 46% of SkySafari 7 Plus's.
APT Darkness Clock ships an update every 11 days, SkySafari 7 Plus monthly. The most recent releases landed on September 8, 2026 and September 26, 2026 respectively.
| Parameter | APT Darkness Clock | SkySafari 7 Plus |
|---|---|---|
| Price | Free — better | $9.99 |
| Rating | 5.0 (4 ratings) — better | 4.7 (1.7K ratings) |
| Positive reviews | 100.0% of reviews — better | 45.7% of reviews |
| Number of ratings | 4 | 1.7K — better |
| Update frequency | Every 11 days — better | Monthly |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Best chart rank | — | #170 — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 10.0 — better | 14.1 |
| Further details — not scored | ||
| Size | 1 MB | 1.1 GB |
| Age rating | 4+ | 4+ |
| Developer | Ivaylo Stoynov | Simulation Curriculum Corp. |
Customer experience
APT Darkness Clock
SkySafari 7 Plus
Bugs and requests
APT Darkness Clock
Not enough reviews yet to summarise bugs or requests.
SkySafari 7 Plus
Reported bugs
4 issues- 'Tonight' feature crashes
- App crashes on launch or when using certain features
- Connectivity issues with telescopes
- Syncing problems between devices
Requested features
5 requests- Add more telescope brands and models
- Improve notification settings to only show relevant events
- Allow hiding of menu bar for cleaner viewing
- Improve font sizes and readability
- Add ability to import observation records from previous versions
In-app purchases
APT Darkness Clock
No in-app purchases
SkySafari 7 Plus
- SkySafari Premium Monthly7 Days trial$4.991 Month
- SkySafari Premium7 Days trial$34.991 Year
- Apollo Lunar MissionsFree
Questions
Is APT Darkness Clock free?
Is SkySafari 7 Plus free?
Which has better reviews, APT Darkness Clock or SkySafari 7 Plus?
Do APT Darkness Clock or SkySafari 7 Plus have ads?
Which is updated more often, APT Darkness Clock or SkySafari 7 Plus?
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