Skip to content
Science for Big BabiesScience for Big Babies

physics

How fast would Swift have to fall to destroy Earth?

NASA's Swift telescope fell back to Earth on Nov 4, 2026 carrying the energy of about 10 tons of TNT. To hit like the Hiroshima bomb it would need about 300 km/s; to blow Earth apart, at least 0.999… of light speed with twenty-four nines.

By Updated 1 min read

The video is in production. Read the full story below in the meantime.

Watch the short

Also onTikTokInstagramX

Key takeaways

  • [One sourced fact per line, a complete sentence.] 1

  • [The misconception, corrected in one sentence.] 2

  • [What it means for the reader.]

The full story

[Short answer in two or three sentences: the question and the answer up front.] 1

The short version

[Baby mode answer: one analogy, no jargon.]

What most people think

[The misconception, why it sounds right, and the evidence against it.] 1

What is actually happening

[The mechanism, step by step, with numbers and their units.] 2

What this means for you

[Consequences, edge cases, what is still debated.]

Mini course · 2 lessons · about 6 min

Learn it step by step

Short lessons at your own pace: guess first, then see why, try the lab, and check yourself at the end of each lesson.

  1. 1.
  2. 2.
Start the mini course

Listen

The audio version is coming soon.

Questions people also ask

[Question people actually search for]?

[Two to four sentences.] 1

[Second question]?

[Two to four sentences.] 2

[Third question]?

[Two to four sentences.]

Sources

Every claim in the video and the article comes from these sources.

  1. NASA. "NASA's Swift Observatory Re-Entered Atmosphere." NASA Swift blog, 2026-11-02, updated 2026-11-04
  2. NASA Science. "The Cast" (Swift Boost Mission), updated 2026-08-13
  3. NASA. "NASA's Swift Mission Ends." 2026-10-23, updated 2026-10-26
  4. NASA GSFC Swift Science Center. Swift Technical Handbook, "Orbital Information"
  5. Smith OE, Adelfang SI, Smith RE. "Neutral Orbital Altitude Density Effects on the International Space Station." NASA-CR-205357, 1997
  6. NASA Orbital Debris Program Office. "Debris Reentry"
  7. NASA Orbital Debris Program Office. "Frequently Asked Questions"
  8. NIST Guide to the SI (SP 811), Appendix B.9: ton of TNT = 4.184 × 10^9 J
  9. U.S. Department of Energy, OSTI. "Manhattan Project: The Atomic Bombing of Hiroshima, August 6, 1945"
  10. Adamsky V, Smirnov Y. "Moscow's Biggest Bomb: The 50-Megaton Test of October 1961." Cold War International History Project Bulletin 4, 1994
  11. CTBTO. "30 October 1961 – The Tsar Bomba" (not readable, 403)
  12. Brown PG et al. "A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors." Nature 503:238–241, 2013
  13. Morgan JV, Bralower TJ, Brugger J, Wünnemann K. "The Chicxulub impact and its environmental consequences." Nature Reviews Earth & Environment 3:338–354, 2022
  14. Durand-Manterola HJ, Cordero-Tercero G. "Assessments of the energy, mass and size of the Chicxulub Impactor." arXiv:1403.6391, 2014 (preprint, not peer reviewed)
  15. Williams DR. "Earth Fact Sheet." NASA GSFC NSSDCA, updated 2024-11-15
  16. NIST. CODATA 2022 recommended values: speed of light, Newtonian constant of gravitation, atomic mass constant
  17. Moebs W, Ling SJ, Sanny J. University Physics Volume 1, OpenStax, 2016, §7.2 Kinetic Energy
  18. Ling SJ, Sanny J, Moebs W. University Physics Volume 3, OpenStax, 2016, §5.9 Relativistic Energy
  19. Thornton ST, Marion JB. Classical Dynamics of Particles and Systems, 5th ed., Ch. 5, Problem 14 (self-energy of a uniform sphere)
  20. Freistetter F. "How Much Energy Would It Take to Blow Earth to Smithereens?" Scientific American, 2024-03-22
  21. Wikipedia. "Gravitational binding energy" (secondary)
  22. Williams DR. "Sun Fact Sheet." NASA GSFC NSSDCA, updated 2024-05-09
  23. Johnson-Groh M. "NASA's Parker Solar Probe Makes History With Closest Pass to Sun." NASA, 2024-12-27
  24. NASA Science. "Orionids"
  25. Bird DJ et al. "Detection of a cosmic ray with measured energy well beyond the expected spectral cutoff due to cosmic microwave radiation." ApJ 441:144, 1995
  26. Keilhauer B (Pierre Auger Collaboration). "The Fluorescence Detector of the Pierre Auger Observatory – A Calorimeter for UHECR." AIP Conf. Proc. 867:175–182, 2006
  27. Munroe R. "Relativistic Baseball." What If? (xkcd) (popular, secondary)
  28. NASA Science. "WMAP Overview"
  29. DLR. "The ROSAT mission – frequently asked questions" (text not readable; 450 km/h figure from press reports, unverified)
  30. Secondary, prevalence check: ScienceAlert / Scott Manley, "How much power does it take to blow up a planet"

Spotted a mistake? Here's how we fix it.

You might also wonder

Space has no air. So why do satellites fall?

Low orbits sit inside the thin top of the atmosphere. Drag steals energy, so satellites sink into lower, faster orbits, where the air is thicker still.