Courses › The Universe from Scratch › Lesson 1
Where are we in the universe? · premieres Monday, October 19
Today we're going to answer a very simple question: where are we? We'll leave Earth, cross the Solar System, reach the nearest star and end up looking at our galaxy from the outside. Every distance in this lesson is measured, and I'll tell you which images are illustration.
To be honest about the images: the Sun and the planets are drawn far larger than reality, because at true scale they would be invisible dots. The galaxy's stars are random points that follow the measured shape of the arms, not real stars one by one. And the dust is missing here: from Earth, dust hides almost the entire centre of the galaxy.
| Figure | Value | Source |
|---|---|---|
| Astronomical unit | 149,597,870.7 km (exact) | IAU Resolution B2 (2012) |
| Sunlight to Earth | 499.0 s = 8 min 19 s | Calculated: 1 AU / speed of light |
| Neptune | 30.07 AU (semi-major axis); light ≈ 4 h 10 min | MHD-INT validation data / NASA Planetary Fact Sheet |
| Pluto | 35.6 AU on 4 Oct 2026 | Outer Solar System template (JPL Small-Body Database elements, Oct 2026) |
| Oort Cloud | 2,000 to 100,000 AU, never observed | Outer Solar System template (marked as a theoretical scheme) |
| Proxima Centauri | 4.2465 light-years (1.3020 pc) ≈ 268,500 AU | Gaia DR3 parallax: 768.0665 ± 0.0499 mas (verified 11 Oct 2026) |
| Proxima's planets | b (confirmed 2016, in the habitable zone) and d (confirmed 2025 with NIRPS); c is still debated | Anglada-Escudé et al. 2016 (Nature); Suárez Mascareño et al. 2025 (A&A 700, A11) |
| Sun to galactic centre | 8.15 ± 0.15 kpc ≈ 26,600 light-years | Reid et al. (2019) |
| Sun's velocity | 236 ± 7 km/s (circular); 247 ± 4 km/s total | Reid et al. (2019) |
| Sun's galactic orbit | 203 million years (calculated); other work gives 220–240 | Milky Way template: 2π R₀ / (Θ₀ + V☉) |
| Large Magellanic Cloud | 49.59 kpc ≈ 162,000 light-years | Pietrzyński et al. (2019), eclipsing binaries |
| Small Magellanic Cloud | 62.44 kpc ≈ 204,000 light-years | Graczyk et al. (2020), eclipsing binaries |
| Milky Way stars | "hundreds of billions" (no exact figure) | Stellar mass 5 × 10¹⁰ solar masses (Bland-Hawthorn and Gerhard 2016) |
They are Solaris Core Blender templates, built from measured data. You can download them, change the camera and make your own images.
See templates