Editing Twin paradox (section)

=== Travellers' perspective ===
The ship's crew members also calculate the particulars of their trip from their perspective. They know that the distant star system and the Earth are moving relative to the ship at speed ''v'' during the trip. In their rest frame the distance between the Earth and the star system is {{nowrap|''α d'' {{=}} 0.6 × 4 {{=}} 2.4 light}} years ([[length contraction]]), for both the outward and return journeys. Each half of the journey takes {{nowrap|''α d'' / ''v'' {{=}} 2.4 / 0.8 {{=}} 3 years}}, and the round trip takes twice as long (6 years). Their calculations show that they will arrive home having aged 6&nbsp;years. The travelers' final calculation about their aging is in complete agreement with the calculations of those on Earth, though they experience the trip quite differently from those who stay at home.