Comparison

Space Telescope App vs RPN 50g

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Space Telescope App

Explore the universe with real-time updates and stunning visuals from NASA's James Webb Space Telescope. Engage with expert insights, join community discussions, and test your knowledge with interactive quizzes. Discover distant galaxies and unlock the secrets of the early universe.

Highlights
  • Live mission updates
  • Breathtaking image gallery
  • Expert Q&A with astronomers
  • Community discussions
  • Interactive space quizzes
  • 3D solar system explorer
  • Exclusive wallpapers
Features
Read full description

Space Telescope is an astronomy app for people who actually go outside and look up. See what the James Webb Space Telescope is observing right now. Decide whether tonight is worth staying out for. Catch the next visible ISS pass over your own location, and follow the rocket launches coming up. WHAT WEBB IS LOOKING AT, RIGHT NOW Webb's current target, science category, proposal, instruments and scheduled times, refreshed every five minutes while the view is open. Tap through to the proposal or the full observation schedule. A REAL PLAN FOR METEOR NIGHT Most meteor apps hand you a peak date. This one tells you what you will actually see. Set your location and how dark your sky is, and get an honest meteors-per-hour range, the best viewing window, where to look, how much the Moon will wash out, and what 30, 60 or 90 minutes outside is likely to be worth. Two alerts that matter: a heads-up the evening before, and a nudge when your window opens. Cloud cover is not included, so check the weather before you commit. THE ISS, OVER YOUR HOUSE Live position, altitude, velocity and orbit, plus crew, expeditions, dockings and visiting vehicles. Seven days of passes for your location with quality, direction, peak elevation and duration - set a 10-minute alert or drop the pass straight into your calendar. LAUNCH DAY Upcoming launches with live countdowns, status, provider, rocket, pad, launch window and webcast link. One tap for a reminder 15 minutes before liftoff. GALLERIES WORTH SCROLLING Imagery and mission guides for James Webb, Hubble, Chandra, the Nancy Grace Roman Space Telescope, Artemis, Mars and the ISS. Follow Roman's countdown, instruments and journey to L2. Pinch to zoom, save, share, like and comment. Turn on alerts only for the galleries you care about. PICTURE OF THE DAY NASA's Astronomy Picture of the Day, image or video, with the full expert explanation and an optional daily alert. AND WHEN YOU WANT MORE - Tonight Sky: sunrise, sunset, Moon phase, illumination and twilight - Space Weather: Kp index, solar wind, aurora probability and active alerts - Cosmic Calendar: meteor showers, eclipses and other sky events - Exoplanets: discovery method and year, distance, orbit, mass, radius, temperature, host star and habitable-zone marker - Community astrophotography: post your own shots with gear and conditions - Space wallpapers for your phone - Quizzes, points, levels and global leaderboards - Ask an Astronomer, and live chat rooms in 10 languages - Full interface in English and Spanish PREMIUM Space Telescope is free, with ads. Premium removes every ad, unlocks the premium wallpaper collection and adds a gold avatar ring. Choose a monthly or annual subscription, or pay once for lifetime access, which also grants 1,000,000 points and Diamond level straight away. Subscriptions are charged to your Apple Account and renew automatically unless auto-renew is turned off at least 24 hours before the current period ends. Manage or cancel in your Apple Account settings. Whether you follow Webb every day, plan a Perseids or Geminids watch, photograph the night sky, teach astronomy, or just want to know when the ISS will cross overhead, Space Telescope keeps the useful details in one place. Space Telescope is an independent astronomy app and is not affiliated with or endorsed by NASA, ESA, STScI, SpaceX or any launch provider. Data and imagery are credited to their respective sources. Privacy policy: https://jameswebbtracker.com/privacy-policy Terms of use (Apple standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

RPN 50g

This app emulates the powerful HP 50g graphing calculator, bringing its advanced features for engineering, physics, and mathematics to your mobile device. It replicates the original hardware and firmware, offering a complete RPN and RPL calculator experience with extensive graphing and programming capabilities.

Highlights
  • Advanced computer algebra system
  • Full scientific calculator functions
  • 2D and 3D graphing capabilities
  • RPL and UserRPL programming
  • Equation Library with over 300 equations
  • RPN or algebraic entry modes
  • SD card file integration
Features
Read full description

The HP 50g is the last and most powerful of a legendary line: HP 48S, 48G, 49G, 49g+ and finally the 50g — a quarter century of RPN and RPL calculators that engineers, physicists and mathematicians never really let go of. Discontinued in 2015, it remains the reference, and many consider it the best calculator ever made. RPN 50g brings that machine to your iPhone and iPad — not an imitation, the real thing. The app emulates the calculator's hardware (its 75 MHz ARM processor, 512 KB of RAM, 2 MB of flash, the 131×80 display, the keyboard and the SD card slot) and runs HP's original firmware, so it behaves exactly as the calculator on your desk: every function, every mode, every flag, every quirk, key click included. THE CALCULATOR • An advanced computer algebra system: exact rational and arbitrary-precision integer arithmetic, symbolic simplification, factoring, polynomials, derivatives, integrals, limits, Taylor series, equation and system solving, linear algebra • An advanced scientific calculator: complex numbers, vectors and matrices, statistics and regressions, unit conversions with dimensional analysis, base conversions (BIN/OCT/HEX) and bit operations, numeric solver, financial (TVM) calculations, date and time arithmetic • Graphing: 2D function, polar, parametric, conic, slope field, differential equations, statistics and 3D wireframe/surface plots, with zoom, trace and analysis • The Equation Library with over 300 equations of physics and engineering, with units • RPN with the four-level or unlimited stack, or algebraic entry with the equation writer, at your choice • Programmable in RPL (UserRPL and SysRPL): your programs and libraries run as on the real machine THE APP • Three faces: the black 50g, the blue 50g and the HP 49g+ — the 49g+ is the same machine, running the same firmware • Firmware versions 2.15 (2009, with the 2 MB fix), 2.10 and 2.09 — switch between them, each keeps its own memory • Your calculator's memory stays: close the app, come back later, it is exactly where you left it • SD card: put files in the app's folder in Files and they appear on the calculator's card; what the calculator writes to the card lands in Files. Install libraries as on the real machine • HP's manuals (User's Guide, Advanced User's Reference…) can be downloaded into the app and read next to the calculator; the app remembers your page • Paste: type text from the clipboard onto the calculator • Hardware keyboard support on iPad and iPhone • The beeper, so BEEP and key clicks sound like the calculator • Works fully offline, no account, no ads, no tracking ABOUT THE FIRMWARE The app contains no HP software. On first launch you pick a firmware version and it is downloaded from GitHub, where the app keeps an identical copy of the package published on hpcalc.org, the community archive that has hosted HP's own update packages for decades (each package checked against its known fingerprint); the image is then kept on your device. HP, HP 48, HP 49g+ and HP 50g are trademarks of HP Inc. This app is an independent project and is not affiliated with or endorsed by HP.

Screenshots

Space Telescope App4 screens
RPN 50g4 screens

Verdict

The call

The clearest difference is review sentiment: RPN 50g at 100% against Space Telescope App's 39%. RPN 50g also leads on rating (5.0 vs 4.1) and in-app purchases (none vs 4). Space Telescope App's advantage is price (Free vs $5.99) and ratings volume (31 vs 1). On update cadence, device support and iOS requirement 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

CostPrice · In-app purchases · Ads · Monetization

Space Telescope App is free to download; RPN 50g costs $5.99 up front. Space Telescope App sells 4 in-app purchases, starting at $4.99 per month. RPN 50g asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

RPN 50g holds the better App Store score, 5.0 against 4.1. That said, the two scores are not equally well evidenced: Space Telescope App has 31 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 39% of Space Telescope App's written reviews are positive against 100% of RPN 50g's.

UpkeepUpdate frequency

Space Telescope App ships an update every 10 days, RPN 50g weekly. The most recent releases landed on November 3, 2026 and November 10, 2026 respectively.

Scorecard7 real differences · 3 level
Space Telescope App versus RPN 50g: the parameters behind the verdict, then further details
ParameterSpace Telescope AppRPN 50g
PriceFree — better$5.99
Rating4.1 (31 ratings)5.0 (1 ratings) — better
Positive reviews38.7% of reviews100.0% of reviews — better
Number of ratings31 — better1
Update frequencyEvery 10 daysWeekly — better
AdsYesNo — better
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
DevicesiPhone, iPad, iPodiPhone, iPad, Mac
Requires iOS15.0 — better16.0
Further details — not scored
Size104 MB30 MB
Age rating4+4+
DeveloperKAKHA GIORGASHVILIGuglielmo Pasa

Customer experience

Space Telescope App

All ratings31 ratings
Positive74.2%
Neutral6.5%
Negative19.4%
Written reviews31 reviews
Positive38.7%
Neutral9.7%
Negative51.6%

RPN 50g

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

4 purchases

Space Telescope App

Subscriptions2
  • Monthly Ad-Free Plan$4.991 Month
  • Ad-Free Annual Access$29.991 Year
One-time2
  • Premium$2.99
  • Buy 1M Points$99.99
None

RPN 50g

No in-app purchases

Questions

Is Space Telescope App free?
Space Telescope App is free to download, with in-app purchases available.
Is RPN 50g free?
RPN 50g costs $5.99, with no in-app purchases.
Which has better reviews, Space Telescope App or RPN 50g?
RPN 50g is rated higher. Space Telescope App averages 4.1 out of 5 from 31 ratings, while RPN 50g averages 5.0 from 1 ratings.
Do Space Telescope App or RPN 50g have ads?
Space Telescope App shows ads; RPN 50g does not.
Which is updated more often, Space Telescope App or RPN 50g?
Space Telescope App ships an update every 10 days, and RPN 50g weekly. Most recently, Space Telescope App was updated on November 3, 2026 and RPN 50g on November 10, 2026.

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