Which planet will not survive the death of the Sun?

Which planet will not survive the death of the Sun?

Mercury and Venus will definitively not survive the death of the Sun. As our star exhausts its hydrogen fuel and enters the red giant phase in about 5 billion years, its outer layers will expand violently, completely engulfing the two innermost planets.

Earths exact fate remains heavily debated among astrophysicists, while Mars and the outer gas giants will safely escape destruction. But there is one counterintuitive factor that most space documentaries overlook when predicting planetary survival - I will explain it in the adiabatic expansion section below.

When I first studied stellar evolution, I assumed the Sun would just explode and obliterate everything instantly. In reality, stellar death is an agonizingly slow process. Our star will burn for another 5 billion years before its core runs out of hydrogen. Once that happens, gravity compresses the core while the outer layers swell outward to approximately 100 to 250 times their current size. The Sun will transform into a glowing red giant, fundamentally rewriting the map of our solar system.

The Inner Planets: Guaranteed Casualties

The planets destroyed when the sun dies will undoubtedly be the closest ones. Mercury orbits at an average distance of 0.39 astronomical units from the Sun, making it the very first casualty. Venus sits at 0.72 astronomical units and will be completely engulfed shortly after. There is no mathematical model where these two worlds escape.

Temperatures on Venus will spike to unimaginable levels before the planet is swallowed whole. The intense heat will strip away its thick atmosphere, melting its rocky surface into a chaotic sea of magma. Once engulfed by the solar plasma, the orbital drag will cause both Mercury and Venus to spiral inward until they are completely vaporized in the stellar core.

Will Earth survive the death of the Sun?

This is where things get complicated. Let us be honest - scientists do not have a definitive answer yet. For decades, the consensus was that Earth would share the exact same fate as Venus. But recent astrophysical models show a much more nuanced picture of what happens to our home planet.

The Cosmic Tug-of-War: Adiabatic Expansion vs Tidal Drag

Here is that counterintuitive factor I mentioned earlier. As the Sun ages, it loses roughly 30% of its total mass through powerful solar winds. Because the Suns mass decreases, its gravitational grip on the planets weakens significantly. This phenomenon, known as adiabatic expansion, means the orbits of all planets will naturally push outward.

Earths orbit will drift outward. Sounds safe, right?

Not quite. The expanding solar atmosphere creates severe friction - known as tidal drag - which pulls planets back inward. Rarely does a cosmic event generate this much scientific debate, but will earth survive the death of the sun depends entirely on which force wins this massive tug-of-war. If mass loss happens fast enough, Earth might migrate out to 1.5 astronomical units and narrowly avoid being swallowed. If tidal drag dominates, Earth gets pulled into the Sun and vaporized.

The Fate of the Outer Gas Giants

While the inner rocky worlds face total annihilation or complete sterilization, the outer solar system will experience a bizarre renaissance. Which planets will survive the red giant phase? Mars, Jupiter, Saturn, Uranus, and Neptune are all safe from being swallowed.

As the Sun balloons in size, the habitable zone - the region where liquid water can exist - will shift drastically outward. It will move past Mars and settle around the orbits of Jupiter and Saturn. Ices on moons like Europa and Enceladus will melt, potentially creating vast liquid oceans for a few million years. Eventually, when the Sun sheds its outer layers and becomes a faint white dwarf, these outer planets will freeze over completely, orbiting a dead star in absolute darkness.

Survival Status of the Eight Planets

Mercury & Venus

• Spirals inward due to extreme plasma drag until vaporized

• Direct engulfment by the expanding solar atmosphere

• Definitively destroyed (0% chance of survival)

Earth

• May drift outward to 1.5 AU, or get pulled inward and destroyed

• Caught between orbital expansion and tidal drag

• Uncertain (Debated among astrophysicists)

Mars

• Pushed further out due to the Sun's mass loss

• Far enough away to avoid engulfment

• Survives but heavily altered

Jupiter, Saturn, Uranus, Neptune

• Orbits expand significantly; atmospheres may briefly warm before freezing

• Massive distance protects them from the red giant boundary

• Completely safe from destruction

Simulating the End of the World

Mark, a physics graduate student, spent three weeks building a computational model to simulate what planets will the sun swallow. He was frustrated because his initial simulation showed Earth surviving easily, which contradicted most published astrophysics papers he had read.

His first attempt only accounted for adiabatic expansion. Because the Sun loses mass, Mark's code pushed Earth's orbit outward to a safe distance. He ran the model five times, always getting the same happy ending, but he knew something was missing.

The breakthrough came at 2 AM when he realized he had ignored the Sun's atmosphere. He rewrote the code to include tidal friction - the drag caused by Earth moving through the outer fringes of the swollen red giant. The math got incredibly messy.

Once he added atmospheric drag, the simulation changed violently. Earth's orbit decayed, and the planet spiraled inward to its destruction. The outcome shifted from a 100% survival rate to less than 10%, teaching Mark that planetary survival is a brutal, chaotic tug-of-war.