As the sites for astronomical observations changed, and astronomers transported their observing instruments from the Earth’s surface to higher and higher into the atmosphere, and then into space, the science they acquired, and the work required, also changed. The search for better seeing and access to the full electromagnetic spectrum inspired astronomers to seek higher ground, first by constructing observatories on remote mountains, then by building instruments lifted by balloons, and finally by instruments to be transported by rockets. Now astronomers observe with tools permanently housed in space. Advances toward and for spaceflight, which brought the astronomer’s eye from mountains to space, reshaped the physical sites of astronomy, what it meant to do astronomical work, and our understanding of the universe itself.

This chapter focuses on the connections between sea surfaces, the atmosphere, and outer space. Its upward-oriented perspective to oceanic history traces these connections from early 20th-century visions like the failed idea of floating airports (seadromes), whose horizontal runways were impractical in aquatic conditions, to later orientation changes. Artificial islands served horizontal helicopter take-off and landing, or offshore rocket launches. The chapter argues that these energy-intensive built environments, enabled by the Age of Oil, spatially and sensually marked the emergence of the oceanic Anthropocene. Platform illumination for helicopters operations, rocket launches, and the flares of oil platforms whose radiation is visible from outer space, created massive “light islands” in marine regions, manifesting carbon emissions. Simultaneously, the light island effect turned into a form of placemaking. Light islands became regular offshore destinations and departure points for other vehicles, creating new oceanic equivalents to terrestrial ports, airports, and spaceports. They also indicated the extension of the human habitat to sea surfaces.

Until now, we’ve only considered the motion of a single particle. If our goal is to understand everything in the universe, that’s a little limiting. In this section, we take a small step forwards: we will describe the dynamics of multiple interacting particles. Among other things, this will highlight the importance of the conservation of momentum and angular momentum.

This chapter explores a core question in astrobiology: what is the future of life on Earth and beyond? The first part describes the cessation of habitable conditions in Earth’s distant future (about a billion years hereafter), and the myriad risks that apparently confront humanity on shorter timescales, ranging from wars and artificial intelligence to asteroid impacts and massive volcanoes. The second segment outlines the possibility of humans migrating to other worlds in the solar system, and the numerous technological and logistical challenges expected to arise during this endeavour. The even more daunting notion of interstellar travel is also touched upon, and the propulsion systems and spacecraft advanced in this regard are sketched. The textbook comes to a close by taking stock of the fates that might await humankind.

Space tourism began in 2001 when an American investment manager paid the Russian space agency US$20 million to travel to the International Space Station on a Soyuz rocket. In 2021, three US-based companies began launching tourists on their own rockets: Virgin Galactic, Blue Origin and SpaceX. The emergence of Space tourism raises difficult issues. One such issue is the environmental effects of launches on the atmosphere and the corresponding implications for climate change. Space tourism also raises difficult questions of international law, including, where does space begin? Who gets to call themselves an ‘astronaut’? Do states have a duty to rescue tourists stranded in space?

More than six decades after Sputnik, most rocket bodies used for space launches are still abandoned in orbit. In 2020, over 60 per cent of all launches to low Earth orbit resulted in at least one rocket body being abandoned in orbit. If that orbit has a sufficiently low perigee, drag from gas in the tenuous, uppermost regions of the atmosphere will gradually reduce the rocket body’s altitude and cause it to re-enter the denser, lower atmosphere in an uncontrolled way. This can occur at any point under its flight path, creating dangers for people on the surface and in aeroplanes. Moreover, many uncontrolled re-entries occur near the equator due to the trajectories of many of the abandoned rocket bodies. As a result, the cumulative risk from rocket body re-entries is higher in the states of the global South, as compared to the major spacefaring states. Yet launch providers have access to technologies and mission designs today that could eliminate the need for most uncontrolled re-entries, albeit at increased financial cost.