The life puzzle: the location of land on a planet can affect its habitability

Artist's impression shows a blue and white ocean covered planet with 2 small grey moons.
Artist impression of a hypothetical ocean planet with a terrestrial atmosphere and two satellites.
Credit
Wikipedia/Lucianomendez

New climate models have found that the amount and location of land on a planet’s surface can significantly impact its habitability. Astronomers have identified substantial differences in surface temperature, sea ice and water vapour across a planet’s surface for different land configurations. The work will be presented on Monday 11 July at the National Astronomy Meeting (NAM 2022) by Evelyn Macdonald, a graduate student at the University of Toronto, Canada.

Many planets are tidally locked to their stars such that one side of the planet is always facing away (much like how the far side of the Moon always faces away from the Earth). This creates permanent day and night sides of the planet where the all energy received from the star is focused on the dayside. In order for a planet to support life, the climate must be somewhat regulated across the surface: the atmosphere and oceans need to redistribute some of the energy received from the star to the nightside of the planet.

A team of researchers at the University of Toronto, have applied a 3-dimensional climate model (ExoPlaSim) to simulated Earth-like planets with two distinct dayside configurations. The first configuration is a circular continent in the middle of the dayside surrounded by ocean. The second configuration is the opposite: a circular ocean in the middle of the dayside with land everywhere else. For both cases, the size of the circle was varied to demonstrate how the planet’s climate depends on land fraction for each of these continent configurations.

Among other things, a planet’s habitability is dependent on its surface temperature and the amount of moisture in its atmosphere. The study models the net precipitation, cloud fraction, and surface temperature across the dayside of the planet for different land configurations.

The results show that both the amount of land, and its configuration can have a large effect on the surface conditions of the planet. For models with similar dayside land fractions but opposing configurations, the average surface temperature can change by up to ~20oC. The results indicate that the amount of water vapour in the planet’s atmosphere heavily depends on the area of ice-free ocean on its surface. Planets with high land fractions have hotter and drier daysides with clouds and precipitation mostly confined to small central areas.

Macdonald says: "Finding out whether life exists elsewhere in the universe is a key challenge of astronomy and science as a whole. Our work demonstrates that the distribution of land on an Earth-like planet has a big impact on its climate, and should help astronomers looking at planets with instruments like the James Webb Space Telescope to better interpret what they're seeing." 


Media contacts

Dr Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7292 3979
Mob: +44 (0)7802 877 699
nam-press@ras.ac.uk

Ms Gurjeet Kahlon
Royal Astronomical Society
Mob: +44 (0)7802 877700
nam-press@ras.ac.uk

Ms Cait Cullen
Royal Astronomical Society
nam-press@ras.ac.uk

 


Science contacts

Evelyn Macdonald
University of Toronto
evelyn.macdonald@mail.utoronto.ca

Prof. Kristen Menou
University of Toronto
kristen.menou@utoronto.ca


Images and Captions

Image link: https://nam2022.org/images/Oceanplanet_lucianomendez.jpeg
Credit: Wikipedia/Lucianomendez
Caption: Artist impression of a hypothetical ocean planet with a terrestrial atmosphere and two satellites.

Image link: https://nam2022.org/images/SOmaps1.jpg
Credit: Adapted from Macdonald et al. (2022)
Caption: Dayside maps of climate variables for land-centred planets. The row labels (left) show the varying dayside land fractions. The columns (left to right) show the land map, net precipitation (precipitation in blue and evaporation in red), cloud cover, and surface temperature. Here, planets with larger continents have less rain and cloud cover, and their daysides are hot and dry.

Image link: https://nam2022.org/images/SCmaps1.jpg
Credit: Adapted from Macdonald et al. (2022)
Caption: Dayside maps of climate variables for ocean-centred planets. The row labels (left) show the varying dayside land fractions. The columns (left to right) show the land map, net precipitation (precipitation in blue and evaporation in red), cloud cover, and surface temperature. Here, daysides are hot and dry when the land fraction is high, but there is always some ice-free ocean present, therefore there is always some level of clouds and precipitation.

Main study: Evelyn Macdonald, Adiv Paradise, Kristen Menou, Christopher Lee, Climate uncertainties caused by unknown land distribution on habitable M-Earths, Monthly Notices of the Royal Astronomical Society, Volume 513, Issue 2, June 2022, Pages 2761–2769, https://doi.org/10.1093/mnras/stac1040

ExoPlaSim reference: Adiv Paradise, Evelyn Macdonald, Kristen Menou, Christopher Lee, Bo Lin Fan, ExoPlaSim: Extending the Planet Simulator for exoplanets, Monthly Notices of the Royal Astronomical Society, Volume 511, Issue 3, April 2022, Pages 3272–3303, https://doi.org/10.1093/mnras/stac172

 


Notes for editors

About NAM 2022

The NAM 2022 conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Warwick.

About the Royal Astronomical Society

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter, Facebook, Instagram and YouTube.

About the Science and Technology Facilities Council

The Science and Technology Facilities Council (STFC) is part of UK Research and Innovation – the UK body which works in partnership with universities, research organisations, businesses, charities, and government to create the best possible environment for research and innovation to flourish. STFC funds and supports research in particle and nuclear physics, astronomy, gravitational research and astrophysics, and space science and also operates a network of five national laboratories, including the Rutherford Appleton Laboratory and the Daresbury Laboratory, as well as supporting UK research at a number of international research facilities including CERN, FERMILAB, the ESO telescopes in Chile and many more.

STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory and the Square Kilometre Array Organisation.

Visit https://stfc.ukri.org/ for more information.

Follow STFC on Twitter: @STFC_Matters

About the University of Warwick

The University of Warwick is one of the world’s leading research institutions, ranked in the UK’s top 10 and world top 80 universities. Since its foundation in 1965 Warwick has established a reputation of scientific excellence, through the Faculty of Science, Engineering and Medicine (which includes WMG and the Warwick Medical School).

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