The Perth Exoplanet Survey Telescope

Searching for New Worlds from a Backyard in the Suburbs

Our home galaxy contains a hundred billion stars. On average each star hosts at least one planet. Over 3000 of these exoplanets have now been discovered.

The PEST Observatory: Image Credit: TG Tan

This website is the story of a little telescope in a suburban backyard that's played a small part in this grand quest.

Why look for planets around distant stars? After all, we have little chance of ever seeing these planets directly, much less visiting.

Because as far as we know, life arises only on planets, warmed by the light of their suns. So the search for planets is also the search for life 'out there'. Confirming there is life spread across the vastness of space will change how we view ourselves and our place in the cosmos.

20th April 2017: Discovery of LHS 1140b

Artist’s impression of LHS 1140b transiting its host, a small, faint red star. Depicted in blue is the atmosphere the planet may have retained. Credit: M. Weiss/CfA

A paper announcing the discovery of LHS 1140b, a super-Earth in the habitable zone around a small nearby star, was published in the journal Nature. This planet is now one of the top candidates in the search for signs of an atmosphere, and for life outside our Solar System. I talk about PEST's role in this discovery here.

There was good Press coverage, including CBC News, and Scientific American.

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By Thiam-Guan 'TG' Tan

An engineer by background, I get a kick out of bringing the vastness of space into reach through stuff that you can put together at home.

PEST is located about 8km from the city of Perth (pop. 1.9 mln), Western Australia. The climate is dry with a decent number of clear nights (144) per year. There is light pollution but this is generally only a marginal issue for the kind of work the observatory does.
PEST has co-discovered 42 Exoplanets;
6 through microlensing and 36 through transits.

Blog Topics

The Observatory

In comparison to most professional telescopes, the PEST is tiny.  And it’s not located on a mountain top away from light pollution.


Photometry is the measurement of light – the brightness of stars.  Very high precision is needed because the transit of a planet across the face of its star will dim the light by only a tiny amount – usually 2% or less. 


PEST was built to find planets.  The easiest to find are hot Jupiters, but the most interesting are Earths.  PEST has helped find both kinds.


A hallowed part of the scientific method, papers are where discoveries are announced and described.


In 2010, when PEST was built, only about 70 transiting exoplanets had been discovered.  I was not sure a backyard telescope could detect, much less discover, exoplanets.