---
title: "Backyard Worlds"
chunk: 1/3
source: "https://en.wikipedia.org/wiki/Backyard_Worlds"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:13:25.266684+00:00"
instance: "kb-cron"
---

Backyard Worlds: Planet 9 is a NASA-funded citizen science project which is part of the Zooniverse web portal. It aims to discover new brown dwarfs, faint objects that are less massive than stars, some of which might be among the nearest neighbors of the Solar System, and might conceivably detect the hypothesized Planet Nine. The project's principal investigator is Marc Kuchner, an astrophysicist at NASA's Goddard Space Flight Center.

== Origins ==

Backyard Worlds was launched in February 2017, shortly before the 87th anniversary of the discovery of Pluto, which until its reclassification as a dwarf planet in 2006 was considered the Solar System's ninth major planet.  Since that reclassification, evidence has come to light that there may be another planet located in the outer region of the Solar System far beyond the Kuiper belt, most commonly referred to as Planet Nine.  This hypothetical new planet would be located so far from the Sun that it would reflect only a very small amount of visible light, rendering it too faint to be detected in most astronomical surveys conducted to date.  However, models of the conjectured planet's atmosphere suggest that methane condensation could in some cases make it detectable in infrared images captured by the Wide-field Infrared Survey Explorer (WISE) space telescope.  Due to the effects of proper motion and parallax, Planet Nine would appear to move in a distinctive way between images taken of the same patch of sky at different times. In addition to Planet Nine, other objects of interest – such as undiscovered nearby brown dwarfs – would also be seen to move in the project's images.

== Project description ==
Citizen scientists accessing the website search through a flip book-style animation of specially-processed mid-infrared images captured by WISE known as unWISE coadds, taken with filters at the wavelengths of 3.4 and 4.6 micrometers. The coadded unWISE images permits fainter objects to be detected than previous processing of WISE imagery allowed. In the flip books these coadds are differenced, a process designed to remove most of signal from stationary objects, leaving moving objects intact. The aim is to identify points of light that move between the flip book frames, including slower-moving "dipoles". Citizen scientists who spot a moving object are encouraged to fill out a "Think You've Got One" form which the project scientists review to confirm if there is motion. The images contain instrumental artifacts and are noisy, which hampers the use of automated image processing software and makes the task ideal for exploiting human visual recognition capabilities. Additionally, to improve the ability to detect objects some participants have created their own tools such as Wiseview, a web-based animation visualization tool.
Once candidates have been identified the science team follow-up the most scientifically interesting objects using ground-based telescopes (at sites such as Mont Mégantic Observatory, Apache Point Observatory, W. M. Keck Observatory, Las Campanas Observatory, Gemini Observatory and the NASA Infrared Telescope Facility) and space telescopes (principally the Spitzer Space Telescope and the Hubble Space Telescope), in order to clarify their nature and assign a spectral type if possible.
The project has been awarded a grant from NASA's Astrophysics Data Analysis Program which will fund it until 2020.
In November 2018, the project was "rebooted", with new images and reduced noise.  By August 2020, more than 100,000 citizen scientists worldwide had taken part in the project.

=== Cool Neighbors project ===
In June 2023 the project "Backyard Worlds: Cool Neighbors" was launched. The "Planet 9" predecessor was focused on finding a hypothesised outer planet, which is not ideal in finding faint brown dwarfs. The new project has switched to focus on searching for faint and cool Y-dwarfs. The new "Cool Neighbors" project pre-selects its images with the help of machine learning.

== Project status ==
In December 2017, seven new brown dwarfs were confirmed, as well as two cool subdwarfs. The spectral types of the new brown dwarfs were T0, T2.8, T5, T6, T6.5, and two of type T8. In addition, there were 337 brown dwarf candidates awaiting spectra for confirmation.
As of the first anniversary of the project in February 2018, the project had discovered 17 brown dwarfs and two cool subdwarfs. The coldest object discovered is of spectral type T9, which raises hopes of discovering type Y dwarfs in the future. In addition, a spectrum was also taken of one possibly variable object of unknown type that does not actually exhibit proper motion. There are 432 objects of interest awaiting verification, of which 38 are Y dwarf candidates.
In July 2018 an update on the project's blog stated that in total 42 brown dwarfs had been spectroscopically confirmed from a list of 879 candidates.  Fourteen of those confirmed are closer to the solar system than 20 parsecs (65 light-years).
As of July 2019, there are 1305 candidate objects to be followed up, of which there are 131 confirmed objects: 70 dwarfs of type T and 61 dwarfs of type L. Of the candidate and confirmed brown dwarfs, 55 of them are closer to the solar system than 20 parsecs. There are also roughly 100 Y dwarf candidates.
At the 235th meeting of the American Astronomical Society in January 2020 a summary of the current status of the project was presented and this included 1503 L, T and Y dwarf candidates. In total 221 spectra have been taken of candidate objects.

== Published discoveries ==

=== WISEA 1101+5400 ===

In June 2017, it was announced that Backyard Worlds had made its first official discovery: a brown dwarf designated WISEA 1101+5400, of spectral type T5.5 and located 34 parsecs (111 light years) from Earth. A paper announcing the discovery was accepted for publication in Astrophysical Journal Letters, and Backyard Worlds now holds the record among all Zooniverse projects as having the shortest time from project launch to first publication.

=== LSPM J0207+3331 ===