You just established a settlement on an Earth-like planetary body far from our solar system. You did your evening chores after eating dinner, and you want to go out for the evening view, which consists of two setting stars, reminiscent of the infamous scene in Star Wars. However, there’s one major difference: a large planetary body is in the sky. As you were aware before arriving, you’re on an exomoon orbiting a Saturn-sized exoplanet, both of which orbits two stars.

While this incredible experience might be centuries away, this hasn’t stopped a large international team of researchers from announcing the discovery of a Saturn-sized exoplanet orbiting two M-dwarf stars, which are smaller and cooler than our Sun. The findings from this incredible discovery were recently published in the Publications of the Astronomical Society of the Pacific and were made using a lesser-known exoplanet discovery method known as gravitational microlensing, or microlensing for short.

The researchers are designating the discovery as the microlensing event KMT-2016BLG-1337L, is located approximately 7,000 parsecs (22,800 light-years) from Earth. The researchers used a series of light curve models to ascertain the masses of the exoplanet, stars, and orbital distances for both.

While the first model estimated the exoplanet is estimated to be 0.3 Jupiter masses and an estimated distance from its host star of 4 astronomical units (AU), the second model estimates the exoplanet is approximately 7 Jupiter masses with an estimated distance of 1.5 AU. For context, the planet Saturn is approximately 0.3 Jupiter masses. Despite this disagreement of the exoplanet mass and orbital distance, both models were consistent in their estimates of the two M-dwarf stars that comprise the binary star system, estimated to be 0.54 and 0.40 masses of our Sun and separated by approximately 3.5 AU.

The study notes, “The event KMT-2016-BLG-1337L underscores the capability of microlensing to reveal planets in dynamically complex stellar environments, including systems that are inaccessible to conventional detection techniques. This expands the census of planets in multiple-star systems and contributes to a more comprehensive understanding of planet formation in such environments.”

As noted, microlensing is a lesser-known exoplanet discovery method, being responsible for confirming just over 250 exoplanets of the more than 6,100 confirmed exoplanets. As its official name implies, microlensing uses the gravity from one star as a lens to magnify the light from a background star when a planet passes in between both stars. Since a star’s gravity is so massive, it warps (or bends) the observed space around it, while also enabling light from behind it through this warped region and be observed from our point of view. This differs from the transit method, which is the most common exoplanet discovery method, as it detects a dip in starlight as a planet passes in front of it. In contrast, microlensing requires two stars for the method to be successful and for an exoplanet to be detected passing between both stars.

While this discovery is notable, KMT-2016BLG-1337L is not the only Saturn-mass exoplanet discovered using the microlensing method, as the researchers note that OGLE-2007-BLG-349L was the first confirmed exoplanet in a binary system, also being a Saturn-sized planet whose findings were published in The Astronomical Journal in 2016. The major difference between the two discoveries is KMT-2016BLG-1337L orbits one of the two stars while OGLE-2007-BLG-349L orbits both stars at once. KMT-2016BLG-1337L orbiting only one star also demonstrates how planets can survive form, evolve, and survive orbiting a single star without the second star influencing its formation and survival.

How many more Saturn-sized exoplanets will be discovered using the microlensing method in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

San Diego County’s water agency is selling some of its water to another Southern California agency to help limit increasingly high water costs for 3.3 million people.

The water is going to Western Municipal Water District, which serves a growing area of nearly 1 million people in Riverside County, including Corona, Riverside and Temecula.

The San Diego County Water Authority will transfer at least 10,000 acre-feet of water per year over the next 21 years, enough for about 30,000 typical households.

The agencies said the deal will be worth about $100 million over the first five years.

The San Diego County agency has invested heavily to get more water in recent decades. In 2003, it struck an agriculture-to-urban transfer deal and it also buys water from the Carlsbad desalination plant under a 30-year agreement. These actions have brought San Diego County plentiful water — also some of the most expensive in the state. At the same time, conservation efforts in San Diego County have reduced water needs.

The San Diego County Water Authority delivers water to 22 cities and other agencies. Last year its board approved raising wholesale water rates 8.3%, which drew criticism from residents who said they were already struggling to afford their water bills.

Board Chair Nick Serrano said the deal “allows us to maximize the value of the investments San Diego County residents made over decades, strengthen water reliability, and do so in a way that is mindful of affordability.”

The two agencies said in a joint statement on Thursday that for Western Municipal, the additional water will help during drought and ensure reliable water without the cost and time involved in developing new water infrastructure projects.

The water will move from one area to the other through the pipelines of the Metropolitan Water District of Southern California, the regional wholesaler that imports water from the Colorado River and Northern California. Both San Diego County and Western Municipal are members of the MWD.

An agreement between the MWD and the San Diego County Water Authority last year ended a 15-year legal battle over water costs and cleared the way for San Diego County to start selling some of its excess water to areas that need it.