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Nature's Astronomical Highlights

The journal Nature has been at the pinnacle of scientific publishing for many years. Founded by an astronomer, Norman Lockyer, it has had an extensive history in publishing the most significant developments in the Natural Sciences. For instance, James Chadwick published his discovery of the neutron in Nature; James Watson and Francis Crick presented the helical structure of DNA. Naturally, astronomy has been no exception: part of the discussion following the “Great Debate” on the nature of the Spiral Nebulae (were these small nebulae within our Galaxy or distant galaxies in their own right?) was contained in Nature’s pages in the early 1920s. In the 1960s, Maarten Schmidt’s discovery of the first quasar and Antony Hewish & Jocelyn Bell’s discovery of the first pulsar were presented in Nature. Even up until the present day, Nature is publishing discoveries that not only are of great interest to professional and amateur astronomers and astrophysicists, but also of relevance to humankind in general. In 2016 we discovered through the work of Guillem Anglada-Escudé and collaborators that the nearest star to our Solar System harbours a rocky planet in a temperate orbit.

It is on the back of these discoveries and this extensive history that Nature Research is launching a new journal in 2017, Nature Astronomy, so that more astronomical research might be published with a similar high standard of editing, peer review and production as Nature’s. To celebrate Nature’s comprehensive astronomical heritage, we at Nature Astronomy have curated this Web Collection of 40 Nature papers that have had significant impact on astronomical research. Several of these papers have been cited over 1,000 times in the astronomical literature. To include some more recent papers, which have not had the luxury of many years over which to accrue citations, we have also consulted Altmetric scores, which gauge social media impact among other things. The result is a Collection of Letters, Articles and Reviews that have been roughly grouped into seven themes: exoplanets, pulsars, black holes & short gamma-ray bursts, long gamma-ray bursts & supernovae, galaxies, dark matter and the large-scale structure of the Universe. Several of these papers have been selected for Free Access for a limited period; these can be found collected together below, or in the “Free access” tab, above. 

Before we delve into these seven topics, there is one stimulating paper that stands apart, written by astronomer and science communicator Carl Sagan and his colleagues (Sagan et al. 1993). It details an experiment performed with the Galileo spacecraft on its way to Jupiter. Galileo was commanded to turn towards the Earth, and capture data with its instruments. Effectively it observed the Earth for signs of life. However, it only just managed to find them: it saw a water-rich atmosphere and surface; it saw signs of biological activity in the high levels of methane; it saw a red-absorbing pigment that might have been responsible for photosynthesis; but the only compelling and indicative detection was that of narrow-band radio emission suggestive of a technological civilisation. The paper presented a unique opportunity to objectively observe our blue marble planet from afar.

Pulsar planets. Credit: NASA/JPL-Catech

Many of us grew up knowing only the nine (now eight) planets of our Solar System. A few are lucky enough to remember the discovery of Pluto, then the 9th planet, by Clive Tombaugh in 1930. “See Another World In The Sky”, the newspapers proclaimed, “Achievement of Century”! Some 62 years later in human history, not one but two new planets were announced in Nature by two US-based astronomers, Aleksander Wolszczan and Dale Frail (Wolszczan & Frail 1992). These planets happened to be significantly further than Pluto, and indeed, not in our Solar System: 2,300 light years away, orbiting a millisecond pulsar at distances of roughly a third and a half that of the Earth’s around the Sun. These were the first two confirmed “extrasolar planets”, found in the uninhabitable regions around a neutron star.

Artist's impression of 51 Pegasi b. Credit: NASA/JPL-CaltechThe discovery of a Jupiter-mass planet around a Sun-like star three years later cemented the foundation of this new study of “exoplanets”. Two researchers in Geneva, Michel Mayor and Didier Queloz, utilised a French telescope to observe the star 51 Pegasi (Mayor & Queloz 1995). Using a spectrograph, they noticed the slight shifts in the star’s spectral lines that indicated an orbiting body – a technique known as the radial velocity method. The planet, they determined, orbited at a distance significantly smaller than that of Mercury in our Solar System. The closing paragraph of their Letter to Nature satisfyingly proclaims the era that they had just been responsible for initiating: “The search for extrasolar planets can be amazingly rich in surprises. From a complete planetary system detected around a pulsar to the rather unexpected orbital parameters of 51 Peg b, searches begin to reveal the extraordinary diversity of possible planetary formation sites."

Cover of Nature issue 7617, from Anglada-Escude et al.To date over 3,500 exoplanets have been confirmed, and they are classified into groups under potentially misleading names like “Super-Earths” and “Hot Jupiters”. More and more detailed properties of exoplanets have been determined: in addition to the minimum mass (from the radial velocity method) and planetary radius (from when planets cross in front of the visible disk of their host star – the transit method), the surface temperature of exoplanets can be determined, the atmospheric composition, the presence of exomoons. Heather Knutson led a team to investigate the diurnal temperature changes of a hot Jupiter (Knutson et al. 2007), deriving day-side and night-side temperatures and constraining the energy transport properties of the atmosphere. Mark Swain, Gautam Vasisht and Giovanna Tinetti detected the first organic molecule, methane, in an exoplanetary atmosphere (Swain et al. 2008). Perhaps the most inspiring exoplanet detection to capture the interest of the general public was the discovery in 2016 of a terrestrial planet in a temperate orbit around our nearest stellar neighbour, Proxima Centauri, by Guillem Anglada-Escudé and colleagues (Anglada-Escudé et al. 2016).