How to feed a growing population healthy food without ruining the planet



File 20190112 43529 sfajtu.jpg?ixlib=rb 1.1
For many of us, a better diet means eating more fruit and vegetables.
iStock, CC BY-NC

Alessandro R Demaio, University of Copenhagen; Jessica Fanzo, Johns Hopkins University, and Mario Herrero, CSIRO

If we’re serious about feeding the world’s growing population healthy food, and not ruining the planet, we need to get used to a new style of eating. This includes cutting our Western meat and sugar intakes by around 50%, and doubling the amount of nuts, fruits, vegetables and legumes we consume.

These are the findings our the EAT-Lancet Commission, released today. The Commission brought together 37 leading experts in nutrition, agriculture, ecology, political sciences and environmental sustainability, from 16 countries.

Over two years, we mapped the links between food, health and the environment and formulated global targets for healthy diets and sustainable food production. This includes five specific strategies to achieve them through global cooperation.




Read more:
How to conserve half the planet without going hungry


Right now, we produce, ship, eat and waste food in a way that is a lose-lose for both people and planet – but we can flip this trend.

What’s going wrong with our food supply?

Almost one billion people lack sufficient food, yet more than two billion suffer from obesity and food-related diseases such as diabetes and heart disease.

The foods causing these health epidemics – combined with the way we produce our food – are pushing our planet to the brink.

One-third of the greenhouse gas emissions that drive climate change come from food production. Our global food system leads to extensive deforestation and species extinction, while depleting our oceans, and fresh water resources.

To make matters worse, we lose or throw away around one-third of all food produced. That’s enough to feed the world’s hungry four times over, every year.

At the same time, our food systems are at risk due to environmental degradation and climate change. These food systems are essential to providing the diverse, high-quality foods we all consume every day.

A radical new approach

To improve the health of people and the planet, we’ve developed a “planetary health diet” which is globally applicable – irrespective of your geographic, economic or cultural background – and locally adaptable.

The diet is a “flexitarian” approach to eating. It’s largely composed of vegetables and fruits, wholegrains, legumes, nuts and unsaturated oils. It includes high-quality meat, dairy and sugar, but in quantities far lower than are consumed in many wealthier societies.

Many of us need to eat more veggies and less red meat.
Joshua Resnick/Shutterstock

The planetary health diet consists of:

  • vegetables and fruit (550g per day per day)
  • wholegrains (230 grams per day)
  • dairy products such as milk and cheese (250g per day)
  • protein sourced from plants, such as lentils, peas, nuts and soy foods (100 grams per day)
  • small quantities of fish (28 grams per day), chicken (25 grams per day) and red meat (14 grams per day)
  • eggs (1.5 per week)
  • small quantities of fats (50g per day) and sugar (30g per day).

Of course, some populations don’t get nearly enough animal-source foods necessary for growth, cognitive development and optimal nutrition. Food systems in these regions need to improve access to healthy, high-quality diets for all.

The shift is radical but achievable – and is possible without any expansion in land use for agriculture. Such a shift will also see us reduce the amount of water used during production, while reducing nitrogen and phosphorous usage and runoff. This is critical to safeguarding land and ocean resources.

By 2040, our food systems should begin soaking up greenhouse emissions – rather than being a net emitter. Carbon dioxide emissions must be down to zero, while methane and nitrous oxide emissions be kept in close check.

How to get there

The commission outlines five implementable strategies for a food transformation:

1. Make healthy diets the new normal – leaving no-one behind

Shift the world to healthy, tasty and sustainable diets by investing in better public health information and implementing supportive policies. Start with kids – much can happen by changing school meals to form healthy and sustainable habits, early on.

Unhealthy food outlets and their marketing must be restricted. Informal markets and street vendors should also be encouraged to sell healthier and more sustainable food.




Read more:
Let’s untangle the murky politics around kids and food (and ditch the guilt)


2. Grow what’s best for both people and planet

Realign food system priorities for people and planet so agriculture becomes a leading contributor to sustainable development rather than the largest driver of environmental change. Examples include:

  • incorporating organic farm waste into soils
  • drastically reducing tillage where soil is turned and churned to prepare for growing crops
  • investing more in agroforestry, where trees or shrubs are grown around or among crops or pastureland to increase biodiversity and reduce erosion
  • producing a more diverse range of foods in circular farming systems that protect and enhance biodiversity, rather than farming single crops or livestock.

The measure of success in this area is that agriculture one day becomes a carbon sink, absorbing carbon dioxide from the atmosphere.

Technology can help us make better use of our farmlands.
Shutterstock

3. Produce more of the right food, from less

Move away from producing “more” food towards producing “better food”.

This means using sustainable “agroecological” practices and emerging technologies, such as applying micro doses of fertiliser via GPS-guided tractors, or improving drip irrigation and using drought-resistant food sources to get more “crop per drop” of water.

In animal production, reformulating feed to make it more nutritious would allow us to reduce the amount of grain and therefore land needed for food. Feed additives such as algae are also being developed. Tests show these can reduce methane emissions by up to 30%.

We also need to redirect subsidies and other incentives to currently under-produced crops that underpin healthy diets – notably, fruits, vegetables and nuts – rather than crops whose overconsumption drives poor health.

4. Safeguard our land and oceans

There is essentially no additional land to spare for further agricultural expansion. Degraded land must be restored or reforested. Specific strategies for curbing biodiversity loss include keeping half of the current global land area for nature, while sharing space on cultivated lands.

The same applies for our oceans. We need to protect the marine ecosystems fisheries depend on. Fish stocks must be kept at sustainable levels, while aquaculture – which currently provides more than 40% of all fish consumed – must incorporate “circular production”. This includes strategies such as sourcing protein-rich feeds from insects grown on food waste.

5. Radically reduce food losses and waste

We need to more than halve our food losses and waste.

Poor harvest scheduling, careless handling of produce and inadequate cooling and storage are some of the reasons why food is lost. Similarly, consumers must start throwing less food away. This means being more conscious about portions, better consumer understanding of “best before” and “use by” labels, and embracing the opportunities that lie in leftovers.

Circular food systems that innovate new ways to reduce or eliminate waste through reuse will also play a significant role and will additionally open new business opportunities.




Read more:
Australian communities are fighting food waste with circular economies


For significant transformation to happen, all levels of society must be engaged, from individual consumers to policymakers and everybody along the food supply chain. These changes will not happen overnight, and they are not the responsibility of a handful of stakeholders. When it comes to food and sustainability, we are all at the decision dining table.

The EAT-Lancet Commission’s Australian launch is in Melbourne on February 1. Limited free tickets are available.The Conversation

Alessandro R Demaio, Australian Medical Doctor; Fellow in Global Health & NCDs, University of Copenhagen; Jessica Fanzo, Bloomberg Distinguished Associate Professor of Global Food and Agriculture Policy and Ethics, Johns Hopkins University, and Mario Herrero, Chief Research Scientist, Food Systems and the Environment, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisements

Why daily doses of nature in the city matter for people and the planet



File 20181120 161612 jduiq9.jpg?ixlib=rb 1.1
Brisbane’s South Bank parkland isn’t exactly getting out in the wild, but experiences of urban nature are important for building people’s connection to all living things.
Anne Cleary, Author provided

Anne Cleary, Griffith University

The environmental movement is shifting away from focusing solely on raising awareness about environmental issues. Many environmental agencies and organisations now also aim to connect people with nature, and our new research suggests daily doses of urban nature may be the key to this for the majority who live in cities.

Every year in the United Kingdom the Wildlife Trusts run the 30 Days Wild campaign. This encourages people to carry out a daily “random act of wildness” for the month of June. The International Union for Conservation of Nature recently launched its #NatureForAll program, which aims to inspire a love of nature.

This shift in focus is starting to appear in environmental policy. For example, the UK’s recent 25-year environment plan identifies connecting people with the environment as one of its six key areas. Similarly, in Australia, the state of Victoria’s Biodiversity 2037 plan aims to connect all Victorians to nature as one of two overarching objectives.

The thinking behind such efforts is simple: connecting people to nature will motivate them to act in ways that protect and care for nature. Evidence does suggest that people who have a high nature connection are likely to display pro-environmental attitudes and behaviours.

Looking beyond the park

What is less clear is how to enhance an individual’s nature connection – that is feeling that they are a part of nature. Over half of all people globally, and nine out of ten people in Australia, live in urban environments. This reduces their opportunities to experience and connect with nature.

Our new study may offer some answers. A survey of Brisbane residents showed that people who experienced nature during childhood or had regular contact with nature in their home and suburb were more likely to report feeling connected with nature.

The study used a broad definition of urban nature to include all the plants and animals that live in a city. When looking to connect urban residents with local nature we need to take a broad view and look “beyond the park”. All aspects of nature in the city offer a potential opportunity for people to experience nature and develop their sense of connection to it.

Raffles Place, Singapore – all urban nature should be seen as an opportunity for nature connection.
Anne Cleary, Author provided

The study also looked at the relationship between childhood and adult nature experiences. Results suggest that people who lack childhood experience of nature can still come to have a high sense of nature connection by experiencing nature as an adult.

There have been focused efforts on connecting children to nature, such as the Forest Schools and Nature Play programs. Equal effort should be given to promoting adult nature experiences and nature connection, particularly for people who lack such experiences.

The benefits of nature experience

We still have much to discover about how an individual’s nature connection is shaped. We need a better understanding of how people from diverse cultural and social contexts experience and connect to different types of nature. That said, we are starting to understand the important role that frequent local experiences of nature may play.

In addition to boosting people’s sense of nature connection, daily doses of urban nature deliver the benefits of improved physical, mental and social wellbeing. A growing evidence base is showing that exposure to nature, particularly in urban environments, can lead to healthier and happier city dwellers.

Robert Dunn and colleagues have already advocated for the importance of urban nature experiences as a way to bolster city residents’ support for conservation. They described the “pigeon paradox” whereby experiencing urban nature, which is often of low ecological value – such as interactions with non-native species – may have wider environmental benefits through people behaving in more environmentally conscious ways. They proposed that the future of conservation depended on city residents’ ability to experience urban nature.

As new evidence emerges we need to build on this thinking. It would seem that the future of our very connection to nature, our wellbeing and conservation depend on urban people’s ability to experience urban nature.The Conversation

The pigeon paradox: interactions with urban nature – here in London’s Hyde Park – may help make city dwellers more environmentally conscious.
Anne Cleary, Author provided

Anne Cleary, Research Fellow, School of Medicine, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Reducing food waste can protect our health, as well as our planet’s



File 20180830 195298 whfufy.jpg?ixlib=rb 1.1
Smaller portions reduce food waste and waistlines.
from http://www.shutterstock.com

Liza Barbour, Monash University and Julia McCartan, Monash University

Globally, one-third of food produced for human consumption is wasted. Food waste costs Australia A$20 billion each year and is damaging our planet’s resources by contributing to climate change and inefficient land, fertiliser and freshwater use.

And it’s estimated if no further action is taken to slow rising obesity rates, it will cost Australia A$87.7 billion over the next ten years. Preventable chronic diseases are Australia’s leading cause of ill health, and conditions such as coronary heart disease, stroke, high blood pressure, some forms of cancer and type 2 diabetes are linked to obesity and unhealthy diets.

But we can tackle these two major issues of obesity and food waste together.




Read more:
Melbourne wastes 200 kg of food per person a year: it’s time to get serious


Avoid over-consumption of food

Described as metabolic food waste, the consumption of food in excess of nutritional requirements uses valuable food system resources and manifests as overweight and obesity.

The first of the Australian dietary guidelines is:

To achieve and maintain a healthy weight, be physically active and choose amounts of nutritious food and drinks to meet your energy needs.

In 2013, researchers defined three principles for a healthy and sustainable diet. The first was:

Any food that is consumed above a person’s energy requirement represents an avoidable environmental burden in the form of greenhouse gas emissions, use of natural resources and pressure on biodiversity.




Read more:
Portion size affects how much you eat despite your appetite


Reduce consumption of processed, packaged foods

Ultra-processed foods are not only promoting obesity, they pose a great threat to our environment. The damage to our planet not only lies in the manufacture and distribution of these foods but also in their disposal. Food packaging (bottles, containers, wrappers) accounts for almost two-thirds of total packaging waste by volume.

Ultra-processed foods are high in calories, refined sugar, saturated fat and salt, and they’re dominating Australia’s food supply. These products are formulated and marketed to promote over-consumption, contributing to our obesity epidemic.

Processed foods promote over-consumption and leave packaging behind.
from http://www.shutterstock.com

Healthy and sustainable dietary recommendations promote the consumption of fewer processed foods, which are energy-dense, highly processed and packaged. This ultimately reduces both the risk of dietary imbalances and the unnecessary use of environmental resources.

Author Michael Pollan put it best when he said, “Don’t eat anything your great-grandmother wouldn’t recognise as food.”




Read more:
Food addiction: how processed food makes you eat more


So what do we need to do?

In response to the financial and environmental burden of food waste, the federal government’s National Food Waste Strategy aims to halve food waste in Australia by 2030. A$133 million has been allocated over the next decade to a research centre which can assist the environment, public health and economic sectors to work together to address both food waste and obesity.

Other countries, including Brazil and the United Kingdom acknowledge the link between health and environmental sustainability prominently in their dietary guidelines.

One of Brazil’s five guiding principles states that dietary recommendations must take into account the impact of the means of production and distribution on social justice and the environment. The Qatar national dietary guidelines explicitly state “reduce leftovers and waste”.

Many would be surprised to learn Australia’s dietary guidelines include tips to minimise food waste:

store food appropriately, dispose of food waste appropriately (e.g. compost, worm farms), keep food safely and select foods with appropriate packaging and recycle.

These recommendations are hidden in Appendix G of our guidelines, despite efforts from leading advocates to give them a more prominent position. To follow international precedence, these recommendations should be moved to a prominent location in our guidelines.




Read more:
Update Australia’s dietary guidelines to consider sustainability


At a local government level, councils can encourage responsible practices to minimise food waste by subsidising worm farms and compost bins, arranging kerbside collection of food scraps and enabling better access to soft plastic recycling programs such as Red Cycle.




Read more:
Campaigns urging us to ‘care more’ about food waste miss the point


Portion and serving sizes should be considered by commercial food settings. Every year Australians eat 2.5 billion meals out and waste 2.2 million tonnes of food via the commercial and industrial sectors. Evidence shows reducing portion sizes in food service settings leads to a reduction in both plate waste and over-consumption.

Given the cost of food waste and obesity to the economy, and the impact on the health of our people and our planet, reducing food waste can address two major problems facing humanity today.The Conversation

Liza Barbour, Lecturer, Monash University and Julia McCartan, Research Officer, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

People, palm oil, pulp and planet: four perspectives on Indonesia’s fire-stricken peatlands


Samantha Grover, La Trobe University; Linda Sukamta, La Trobe University, and Robert Edis

Peat means different things to different people. To many Irish people, it means fuel. To the Scottish, it adds a smoky flavour to their whisky. Indonesia’s peatlands, meanwhile, are widely known as the home of orangutans, the palm oil industry, and the persistent fires that cause the infamous Southeast Asian haze.

Indonesians, and other people with ties to these peatlands, have a range of perspectives on the value of peat – both commercial and otherwise.

Here we explore them through the eyes of four fictitious but representative characters.


Read more: How plywood started the destruction of Indonesia’s forests.


The smallholder in rural Sumatra

Peatland is my land. As migrants from Java, my family now have our own house and our own crops. In some years there have been terrible fires, with smoke so thick we can’t even see the end of our street, and all of our food crops burn. But in other years, the rice and corn grow well, my family eat fish every day, my wife smiles, and our children grow tall.

In Java we had no land of our own, and I worked as a farm labourer. Here in Sumatra we have our own peatland. It is different from Javanese soil but we work hard to tend our crops, watering them in the dry season and protecting them from fire.

A big palm oil company has trained me and 50 other men from our village in firefighting. We have uniforms and water-holding backpacks, and I have learned about when the fire will come. They are helping us to protect our palms, and their own palms, of course. My palms are still young, but in a few years I will sell the palm oil fruit to the company, and then my boys can go to high school in town – as long as the palms don’t burn, God willing.

Floods are a harder problem. How can I protect my land? The government dug canals to drain the peatland before we came, but they are not big enough to hold all the water that comes from the heavens and the floods come more and more often.


The official in Jakarta

Peatland is our burden. Indonesia has fertile land, rich oceans… and then there are the peatlands. It is always either too wet to use, or so dry that it burns.

Other Southeast Asian governments want us to end the fires and haze single-handed, but Indonesia isn’t the only one to blame; peatland fires are a regional problem.

We are caught between domestic and international pressures. Develop our peatlands to lift our people out of poverty, or preserve them for orangutans and carbon storage. Of course, the Indonesian people are my priority.

When I studied agriculture at university in Brisbane in the 1990s, my classmates were a little fuzzy about where Indonesia is, let alone what happens here. Now, when our ministry visits Canberra, I feel sad to see “Palm Oil Free” displayed prominently on supermarket products. Westerners don’t understand that not all palm oil is grown on peatlands, that it is a healthy oil and a highly efficient crop perfectly suited to tropical conditions.

Oil palms can be grown sustainably and have helped many farmers out of poverty. Nearly half of Indonesia’s palm oil is sourced from smallholders, and losing that income can really hurt them.

A palm growing on peatland.
Andri Thomas, Author provided

Our ministry is working hard to ensure that Indonesia develops our peatlands sustainably, restoring and rewetting degraded areas and working with the local people to find economic uses for wet peat. My son wants to follow in my footsteps and work on peatlands too, and has applied to study sustainable development at university in Singapore.

So while peatlands are currently a source of national embarrassment, many minds are focused on transforming them into the goose that lays the golden egg for Indonesia.


Read more: Sustainable palm oil must consider people too.


The businessperson in Singapore

Peatland is good, profitable land. For too long we have considered it wasteland – too wet, too far away. But technology from peat-rich countries like Finland and Canada is helping us to use tropical peatlands for people.

My pulp and paper company has half of its plantations on peatlands, which produce more than a third of our pulpwood. My silviculture (forest management) team works closely with my environmental manager and PR team to ensure that our plantations are grown according to best practice, and that our shareholders and clients know it.

The community benefits in the regions around our plantations are easy to see. The village that my parents came from has electricity now, and big modern houses have replaced the old wooden ones. We have paved the road and our taxes support the government’s new health centre and primary school.

We are not a big company like Asia Pulp and Paper, which can afford to retire part of the estate on peatlands, but we do try to abide by the 2011 moratorium on new plantations on peatlands, despite repeated scepticism from environmental groups. Anyway, the moratorium is a Presidential Instruction, and so is flexibly applied.

The Indonesian government doesn’t want any more fires, and neither do we – we don’t want our plantations to burn! But the new regulations that require rewetting the peat are a big challenge for us. What will grow in wet peatland?

I lie awake at night worrying about my company’s future. What species can we diversify into? Should we move away from pulp and into bioenergy? Are we putting enough money into R&D? Should I spend more on lobbying? My son is studying for an MBA in the United States, but will there still be a profitable business for him to join when he graduates?


The orangutan carer

A youngster in the forest.
Michael Catanzariti/Wikimedia Commons, CC BY-SA

We rescued Fi Fi from an area that used to be peatland forest but has been cleared for palm plantations. With no food and nowhere to make a nest, Fi Fi and her mother gradually got weaker and weaker, until workers at the plantation noticed and called us. The mother died before we could help her.

That was nine months ago, and I’ve been caring for Fi Fi around the clock since then in a babysitting team with my friend Nurmala. Fi Fi loves cuddles, milk and fruit, just like my children did at her age.

It is a good job, and we have a great team. Everyone is passionate about protecting the orangutans and the forest. We would like to be able to release Fi Fi once she has learned all her forest skills. Orangutans can look after themselves from about seven years old. But they need a lot of space.

Peatland fires, logging and oil palm planting destroy more forest every year, so places for Fi Fi to be released are hard to find. My brothers and sisters are all happy to stay living near our family home, and when I’m not here looking after Fi Fi, I always have my nieces and nephews on my knee.

I love to have them close, but when the dry season fires come and the haze is so thick I can’t even see my brother’s house across the street, I sometimes wish they had flown a bit further from the nest. Last year we were in and out of the health clinic for a month with my niece’s breathing problems.

I spend all my time caring for precious little ones – both human and orangutan – but the issues themselves are too big for me to fight.


Read more: Good news for the only place on Earth where tigers, rhinos, orangutans and elephants live together.


A way forward?

People are central to the problem of tropical peatland fires. In their natural state, tropical peat swamp forests are too wet to burn. Drainage, installed by people for forestry, palm oil, roads, mining and other development, lowers the water table and dries out the peat. Many peat fires smoulder for months, from the start of dry season in July until the monsoon returns in November.

These fires have a wide range of negative effects: on local health, regional economies and the global carbon cycle. Indonesia’s president, Joko Widodo, has created a new Peatland Restoration Agency, and announced policies to restrict burning and draining of the peat beyond a maximum water table depth of 40cm below the surface. However, action is still disjointed and ministries are, at times, working at cross purposes.

The truth is that only when enough people value wet peatlands will the fires be prevented. Wet peatlands are great for orangutans and the global climate, but how about local smallholders, government officials and business investors? Saving peatlands will require creating value for these people too.

What crops can be profitably grown with a water table high enough to prevent burning? How can smallholders tap into a carbon trading market? Rather than cutting trees to send their children to school, can they earn more money by protecting the carbon stored in peat? Can villagers be empowered to make a better living from ecotourism than illegal logging?

Humans are integral to Indonesia’s tropical peatlands. And they must be at the centre of the solutions too. Otherwise the fires will keep burning – and none of the four people whose stories we’ve heard want that.


The ConversationThis article was co-authored by Laura Graham of the Borneo Orangutan Survival Foundation and Niken Sakuntaladewi, a researcher with the World Agroforestry Centre.

Samantha Grover, Research Fellow, Soil Science, La Trobe University; Linda Sukamta, Lecturer, Humanities and Social Sciences, La Trobe University, and Robert Edis, Soil Scientist

This article was originally published on The Conversation. Read the original article.

Somewhere out there could be a giant new planet in our solar system: so where is it?


Tanya Hill, Museum Victoria and Jonti Horner, University of Southern Queensland

There’s plenty of excitement at the announcement overnight that a new planet is potentially waiting to be found at the extremes of our solar system.

The possible ninth planet is thought to be quite substantial with a mass around ten times that of Earth and a radius that’s two-to-four times bigger than Earth’s. This characterises it as a Neptune-like object.

What’s truly remarkable about Planet Nine, as it has been dubbed, is its very long orbit. It is estimated to take between 10,000 to 20,000 years to orbit our sun, on an elliptical orbit that stretches way beyond the Kuiper Belt.

The Kuiper Belt is a ring of icy objects (which includes Pluto) that circles the sun beyond the orbit of Neptune. Neptune orbits about 30 times further from the sun than the Earth and astronomers refer to Neptune’s distance from the sun as being 30 astronomical units (au) (where one au is the Earth-sun distance). Pluto follows an elliptical orbit that brings it as close as 29.7au from the sun, then out to almost 50au at its most distant point.

Planet Nine’s proposed elliptical orbit takes it from 200au at its closest to the sun (or perihelion) and between 500au to 1,200au at its furthest (aphelion). When it comes in close, it should be bright enough for high-spec backyard telescopes to pick it up.

But unfortunately, most of the time the planet will be much more distant and that represents a greater challenge. It will require the world’s largest telescopes, such as the 10m diameter Keck telescopes and Japan’s 8.2m Subaru telescope (both located on Mauna Kea in Hawaii) to have a hope of seeing it.

Ghostly pull of gravity

The planet has yet to be seen. So why is it thought to be out there? And how can we know so much about it? Planet Nine is the best fit to explain the orbits of six distant objects.

The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta) all mysteriously line up in a single direction. Also, when viewed in three dimensions, they all tilt nearly identically away from the plane of the solar system. Batygin and Brown show that a planet with ten times the mass of the earth in a distant eccentric orbit anti-aligned with the other six objects (orange) is required to maintain this configuration. The diagram was created using WorldWide Telescope.
Caltech/R. Hurt (IPAC)

What’s odd about these six objects is that they have peculiar but remarkably similar orbits. These objects have been nudged off kilter and yet they are all shepherded together in the same region of space.

The first of these objects to be discovered was Sedna. It was observed in 2003, as it approached perihelion. When its 11,400-year orbit was calculated, the discovery team realised that this object was orbiting in a kind of “no man’s land” (or more correctly “no person’s land”).

It was too distant to belong to the Kuiper Belt and not far enough away to be among the sphere of comets orbiting the sun in the Oort Cloud.

Sedna was also beyond the gravitational pull of Neptune, so something else, perhaps a large planet or possibly even a passing star (one of the sun’s many siblings perhaps), might have nudged it off course. What makes Planet Nine feasible is that it can explain the orbit of Sedna along with the other five objects.

At their closest approach to the sun, these six objects sit within the plane of the solar system. Planet Nine would have an orbit that is anti-aligned to the six objects and provides the gravitational tug needed to keep those planets in check.

And there’s more. What makes good science is when a proposed model explains something above and beyond its original intention. Simulations of Planet Nine predict that there should also be objects in the Kuiper Belt that have orbits perpendicularly inclined to the plane of the solar system.

Turns out, these objects exist. Five such objects have been known about since 2002, although their orbits have been unexplained until now.

A predicted consequence of Planet Nine is that a second set of confined objects should also exist. These objects are forced into positions at right angles to Planet Nine and into orbits that are perpendicular to the plane of the solar system. Five known objects (blue) fit this prediction precisely. This diagram was created using WorldWide Telescope.
Caltech/R. Hurt (IPAC)

Haven’t we seen this before?

If Planet Nine does exist, it’s not the first time that a planet in our solar system has been discovered theoretically before being directly observed. In 1845, deviations in the orbit of Uranus, suggested there might be an eighth planet to the solar system and in 1846, Neptune was observed exactly where it was predicted to be.

There have also been predictions that haven’t stood the test of time. Back in the 1980s, scientists proposed that the sun might be a binary, with a dim undiscovered companion moving along on elongated orbit. Every 23 million years (or so), this star named Nemesis would pass through the solar system causing a deluge of comets to impact Earth and produce mass extinctions.

More recently, around the turn of the millennium, astronomers noticed an asymmetry in the distribution of new comets coming in from the Oort Cloud. In theory, comets should come evenly from all directions, but there was a slight excess distributed around a great circle on the sky. One of the explanations was that there could be a Jupiter-mass planet in the Oort cloud, known as Tyche.

In 2014, NASA’s Wide-Field Infrared Survey Explorer (WISE) examined the entire sky across infrared wavelengths. It was the perfect telescope to detect Nemesis or Tyche, but failed to find any evidence of either.

Will we find Planet Nine?

Scientists are sceptical by nature. It’s exciting to have a model that predicts the existence of Planet Nine but this prediction must also be tested. Astronomers have begun searching through astronomical surveys, such as the WISE survey, the Catalina Sky Survey, and the Pan STARRS surveys in the hope of making a sighting.

So far, nothing has been seen. The conclusion, as described in a blog by astronomer, Mike Brown (who proposed Planet Nine along with colleague Konstantin Batygin) is that Planet Nine, if it exists, is likely in the hardest place to find.

It seems to currently be at its furthest point from the sun, at least 500au away; it’s probably fainter than 22nd magnitude (that’s 1,500 times fainter than Pluto); and very possibly it’s aligned with the plane of the Milky Way Galaxy (meaning that Planet Nine may currently be hidden against the background stars of our Galaxy).

Regardless, the hunt is on and there just may be a great discovery out there, waiting to happen.

The Conversation

Tanya Hill, Honorary Fellow of the University of Melbourne and Senior Curator (Astronomy), Museum Victoria and Jonti Horner, Vice Chancellor’s Senior Research Fellow, University of Southern Queensland

This article was originally published on The Conversation. Read the original article.