This blog, first published July 4, was updated on July 25 to reflect the findings from Citizen Astronomers’ observations of exoplanet candidate TOI 1812.01 on July 17. Read more about their results below – we still need more observations of this exclusive planet on August 2!
Credit: NASA JPL / Caltech
This August, Unistellar observers around the world have the chance to help discover not one, but two important pieces of information about a distant exoplanet candidate. The exoplanet in question, which was found in 2020 by NASA’s planet-hunting TESS mission, is named TOI 1812.01. It’s thought to be a cool Jupiter, a rare class of exoplanet that could have moons with the conditions right for life.
On August 2, the distant world may transit, or pass in front of, its star, giving astronomers an opportunity to study it. TOI 1812.01 is still an exoplanet candidate, meaning astronomers need more information to confirm its existence — so the first piece of information they’re looking for is simply whether it exists or not!
As an exoplanet passes in front of its star, it blocks out a portion of the star's light.
But there’s another big mystery surrounding this exoplanet. With just two observations from TESS, astronomers can’t yet determine TOI 1812.01’s orbital period, which is how long it takes the planet to orbit its star — current estimates range from 71 to 157 days. But if we do see a transit on August 2, observers on Earth will be able to confirm the period at 87 days, giving scientists important new information about the exoplanet.
The transit would be visible across a large swath of the Earth, but the catch is that it would take 16 hours, too long for observers in any one place to observe before the sun rises. So, multiple observers spread out across the world are needed — exactly like the Unistellar Network.
In fact, 15 Citizen Astronomers from North America and Europe observed TOI 1812.01’s star on July 17 for over 12 hours in search of a transit. Since they did not observe a transit, it must take this exoplanet longer than 71 days to orbit its star. Now that the Unistellar Network has ruled out a 71-day-long year for this world, scientists need more observations to find out how long its year really is!
An August 2 transit, indicating an 87-day period, would first be visible in Japan and East Asia, continue across Eastern Europe, and finish in Western Europe. Observations from Citizen Astronomers in Japan, East Asia and Western Europe will be particularly important for piecing together the beginning and end of the transit. If that’s you, Unistellar could use your help! But if it’s not, don’t fret – in case TOI 1812.01 does not transit on August 2, its passage will occur later in the year and be visible to a different part of the globe.
Observing TOI 1812.01
If this is your first time observing an exoplanet transit, first check out our Exoplanet Tutorial page for an overview of the techniques involved. Then, head to Unistellar’s Exoplanet Predictions page, select your location and click on the row for TOI 1812.01 – 2 August to find the observation settings and visibility map.
Our goal is to observe TOI 1812.01’s star during the times when the exoplanet is most likely to transit, based on astronomers’ calculations of its possible orbital periods. With your observations, we’ll be one step closer to knowing how long a year is on this faraway world!
The visibility map of TOI 1812.01's transit. The orange diamonds denote partial visibility of the event, where an observer at that location will see a portion of the transit. Yellow diamonds denote full visibility, although tracking issues may occur due to the target's high altitude.