Live planetary positions ·

North ecliptic view · distances compressed · planet sizes enlarged

Moon systems use separate enlarged scales. Diamond markers identify spacecraft.

Time & sharing

Selected time is shared by both explorers and the Astra background. Sol’s background stays live. Spacecraft snapshots keep their recorded timestamps.

Object information
Replay a mission
Build a trajectory

Experiment with a route between planets, then examine how a close encounter changes its course. These simplified models explain orbital mechanics; Replay a mission uses recorded historical trajectories.

Chain gravity assists

Build consecutive encounters. Each flyby changes the vessel’s outgoing orbit, which determines which planet orbits it can reach next.

    Sun-centered linear distance scale; markers are enlarged. Departure is a tangential impulse from Earth’s circular solar orbit. Sun-only propagation connects instantaneous, unpowered flybys. Planet phases are freely placed at encounter points, so this tests an idealized sequence rather than real launch dates. Rings, atmospheres, moons and multi-body perturbations are excluded. Positive solar orbital energy means Solar System escape, not escape from the Milky Way. Limit: 10 encounters, 80 years per leg.

    Sources: NASA · Gravity assists · JPL

    Mission designer

    Plan a circular, coplanar transfer. The explorer date sets the starting planetary longitudes; ideal alignment places the destination where the spacecraft can meet it.

    Gold: spacecraft. Blue: departure planet. Red: destination planet. Distance scale is linear; markers are enlarged. The thin line at arrival shows the miss distance when alignment is wrong.

    Advanced: destination flyby

    Assume ideal alignment and skip the arrival burn. Change flyby altitude to see the outgoing solar orbit. This explores one encounter, not an optimized multi-planet mission.

    Hohmann transfer model: circular orbits, impulsive burns and Sun-only gravity between encounters. Velocity changes are relative to circular solar orbits, excluding surface launch, capture, parking orbits and propulsion losses. Flyby output uses a patched two-body approximation. These are educational estimates, not real launch windows or flight plans.

    Sources: NASA · Trajectories · JPL · Astronomy Engine

    Gravity-assist playground

    Bend a spacecraft’s path around a moving planet. Compare its incoming and outgoing speeds in each reference frame.

    Gold dot: spacecraft. Blue dot: planet. Planet motion points right. Paths share a linear distance scale; markers are enlarged.

    Idealized unpowered flyby: spherical gravity, circular planet orbit and constant planet velocity during the encounter. Atmospheres, rings, moons and solar tides are excluded. Jupiter uses its system mass. The speed comparison uses asymptotic approach and departure, far from the planet; local speed rises near closest approach. This is a learning model, not mission navigation.

    Sources: NASA · Gravity assists · JPL · Astrodynamic parameters · JPL · Planet sizes

    Beyond the Solar System

    Does leaving the Sun also mean leaving the Galaxy? Start with an outward solar speed, coast through a model galaxy, then compare the route after a hypothetical stellar encounter.

    Gold dot: vessel. Center dot: model center. Gray ring: starting orbital radius. Dashed path: coast without the latest encounter. Distances share a linear scale; markers are enlarged. 1 kpc is about 3,262 light-years; 1 Myr is one million years.

    Try a hypothetical stellar encounter

    Place a Sun-mass star at the vessel’s current position. Its motion is tangent to the model center; a negative speed reverses that direction. The encounter rotates the vessel’s relative velocity without changing its magnitude in the star’s frame.

      Model and limits

      This is a spherical Hernquist thought experiment, not a fitted Milky Way model or a flight plan. The starting radius is 8.2 kpc, circular speed 220 km/s, and scale radius 20 kpc. Imported solar speed is aligned with galactic rotation; the planetary route’s direction and travel time are not transferred. Stars are placed by hand, with instantaneous unpowered flybys. No real star rendezvous, disk, central black hole, radiation, propulsion or relativity is modeled. Limit: 20 steps. Escape means nonnegative orbital energy in this model, not crossing a drawn boundary.

      Sources: Hernquist potential · galpy · NASA · Gravity assists

      Sources: Astronomy Engine · NASA/JPL Horizons · Coordinates and ephemerides

      Astra

      Looking up · north at top · east at left · horizon at the edge

      Astra settings also control the site background and follow you between pages. Selected time is remembered in this tab for up to a day. Live restores the current sky.

      Location applies to the background and explorer. Automatic uses an approximate location; Charleston is the fallback.

      Live

      Timelapse updates this sky and the site background. Pause to inspect the sky; Live now returns both to the current time.

      Time & sharing

      Selected time is shared by both explorers and the Astra background. Sol’s background stays live. Spacecraft snapshots keep their recorded timestamps.

      Viewing highlights

      Next 24 hours from the selected time and location. Suggestions require the Sun below −12° and the object at least 20° above the horizon. Times are approximate, sampled every 15 minutes, and shown in UTC. Weather, terrain, and light pollution are not modeled.

      Sources: Astronomy Engine · NASA · Skywatching

      Discover a constellation

      Trace all 88 constellation figures. Patterns are available when every star is at least 10° above the horizon and fits in your current view. Choose a constellation or discover a mystery pattern. This is a geometric learning map, including during daylight.

      Observer world and surface coordinates

      Uses the explorer time and a spherical surface observer. North is up; east is left when looking upward. This geometric vacuum sky shows stars even in daylight. Atmosphere, terrain, refraction, aberration and light-time are excluded. Stars retain catalog J2000 directions; planetary positions include the observer’s surface offset. These settings control the main Astra map and the site background.

      Sources: Astronomy Engine · IAU 2015 · d3-celestial

      Object information

      Sources: Astronomy Engine · d3-celestial / XHIP · IAU

      Signal received

      Amaze.

      A signal found its way through the dark.

      A small tribute to Project Hail Mary by Andy Weir.

      Projects

      Selected work that highlights my skills.

      VeriMarc Attestation Microservice

      A containerized Go microservice for CAMA Security’s VeriMarc platform, guaranteeing reliable, ordered message delivery to embedded devices over intermittent connectivity.

      gobackendsecurityAWS

      AISAI: Automated Identification of Software Supply Chain Vulnerability

      Researching static-analysis + LLM-assisted detection of Python supply chain vulnerabilities; benchmarking effectiveness across models.

      researchsupply chain securitypython

      Malicious Python Package Detector

      Dash-Cytoscape interface with LangChain, Ollama, and Bandit, paired with scikit-learn Random Forests to flag malicious Python code.

      machine learningsupply chain securitypython

      Appearance

      Changes apply across the site and are saved in this browser.

      Theme and motion
      Sky backgrounds

      Names the visible star patterns in dark mode. Keep the background above Minimal to see them.

      Shows enlarged Earth and Jupiter moon orbits in Sol’s background. Turning this on selects High detail.

      Rendering and effects
      Reading and contrast

      Reset restores appearance and sky defaults. Saved reading positions and demo setups remain available under Local data.

      Local data

      These items are stored only in this browser. Choose what to remove.

      Reading positions

      Removes saved article positions in both languages.

      Search history

      Removes recent searches and turns off search-history saving.

      Preferences

      Resets appearance and reading controls to their defaults.

      Saved demo setups

      Deletes saved boards, setups, and remembered demo settings. Export anything you want to keep first.

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