The next time someone asks you where the biggest ocean is, point them toward Jupiter. While earth harbours about 320 million cubic miles(1,333 cubic km)of water, our planet is practically a desert compared to the rest of the Solar System.

A moon of Jupiter called Europa, for example, which is roughly the size of our own Moon, likely hides a subsurface ocean with more than twice as much water as there is on Earth.

Yet even that pales into insignificance in comparison to Europa's neighbour Ganymede; more than 30 times as much water as our home planet is thought to reside there as liquid and ice.

And scientists keep finding more water wherever they look. On September 28, researchers reported that Dione — a small moon of Saturn — probably has a subsurface ocean, too.

To see just how Earth stacks up against other ocean worlds, Business Insider contacted Steve Vance, a planetary scientist at NASA's Jet Propulsion Laboratory who's calculated the numbers on just how much water might be out there.

In order of how much water they have, from the least to the most, they are: Enceladus, Dione, Earth, Europa, Pluto, Triton, Callisto, Titan, and Ganymede. Mimas, a moon of Saturn, and Ceres, the largest asteroid in the Solar System, are also thought to have subsurface oceans —but scientists aren't yet sure how big each one might be.

It encouraged us to visit Quora.com, the online question and answer community, to find out how users get the most out of every tank of gas.

Light makes right

Alex Elderfield noted that excess weight prevents an engine from burning fuel efficiently. "Only carry what is essential in your car, clean out any junk or necessary items otherwise you are paying for the fuel to cart these from place to place," he wrote.

Driving smoothly — that is, not mashing the gas and then slamming the brakes later down the road — was a fixture of many responses. Quora user Clint Law agreed on that advice, who wrote, "Every little bit of kinetic energy that your brakes lose, your engine burned in fuel to build up." Overbraking should consequently be viewed as wasted acceleration. "That's really what kills your fuel economy," he argued.

Keep the pressure up

Keeping the recommended tire pressure for your car was another mantra among Quora users. Marlyn Rosent said she checked her tire pressure every time she filled up her SUV. Quora user Doug Dingus checks his tire pressure every weekend. “Less tire contact means reduced rubbing, requiring less fuel,” he said.

Air conditioning or windows

Though the summer heat get many drivers to roll up the windows and turn on the air conditioning, some people argued that running the A/C wastes too much gas. In between were many shades of grey.

Achilleas Vortselas said it would depend largely on a car’s speed. He wrote that as a general rule, people should drive with the windows down around the city and turn the air conditioning on when hitting the highway, where a car’s aerodynamic(空气动力的) characteristics would be influenced by opened windows.

More seriously minded people, however, said to travel as much as possible with windows up and the A/C off. Eddie Xue gets by with just a wisp of outside air. “Use the fan and open your windows every now and then at lower speeds," he wrote.

China has the highest adoption rate in the world for technology-enabled payment systems, according to a report released on Wednesday. The report, from the market research firm Nielsen, is based on a survey of 13,000 respondents in 26 countries.

The survey showed that 86 percent of Chinese respondents said they paid for online purchases during the past six months via digital payment systems compared with a global average of just 43 percent.

"Chinese consumers have more payment choices for products and services than ever while digital payments will continue to win over more Chinese consumers due to its convenient nature," said Kiki Fan, managing director of Nielsen China.

The increasingly popular payment method is part of the rapidly evolving purchasing behavior of Chinese consumers. About 98 percent of the respondents in China, the world's largest e-commerce market, said they had made purchases online.

The majority of them still make online purchases via computers, but the number of those who use mobile devices to make purchases is growing fast and is significantly higher than the average in other surveyed countries.

At 71 percent, food-related businesses topped the list of purchases made via smart phones while event ticket purchases stood at 51 percent.

The rising use of digital payments has attracted numerous players to the Chinese market.

Apple Inc launched its contactless payment system Apple Pay in the Chinese mainland last month. It allows users of the iPhone 6 or more advanced versions, certain iPads and Apple Watches to pay by their devices in bricks-and-mortar stores.

Apple's rival Samsung Electronics Co Ltd is expected to bring its own mobile payment service to China in mid-March—Sam-sung Pay.

China's Internet giants Alibaba Group Holding Ltd and Tencent Holdings Ltd have already taken about 90 percent of the mobile payment market, but industry observers said the competition is just about to start.

If you’re encouraged by the tiny house movement and think 160 square feet is just enough for your needs, you may want to contact the Academy of Construction and Design (ACAD) at IDEA Public Charter School in northeast Washington.

Students in the program built a micro house with a kitchen, a bathroom, a sleeping loft with space for a queen-size bed and a storage loft, all set on a trailer for mobility. The exterior of the house was part of a continuous living exhibit in 2015 and was moved to the IDEA campus so students could work with builders to complete the interior earlier this year.

McMahon said the D. C. government’s approval to push companies to hire District residents was at odds with the school system not preparing students for careers in construction, exploring or electrical work. McMahon gathered industry and community leaders to establish ACAD in 2005, and he said 100 percent of the companies he contacted responded positively to the idea, including major firms such as JBG, Clark Construction, Hines Construction and Boston Properties.

“When students make the connection between what they are learning a potential career, their academics improve dramatically,” said Carol Randolph, chief operating officer of the D. C. Students Construction Trades Foundation. “Some of them who didn’t think college was an option now have a better chance because their classes have become relevant to a job.”

“We teach them life skills and explain that even if you start as a laborer, there are opportunities to move up quickly,” he said. “We rewrite the story for them and explain that they can work for a few years, make good money, get promoted, and start their own business or go to school with less debts.”

“Parents and school advisor can be the biggest obstacles because of the negative idea of construction as a blue-collar career,” Karriem said. “I get middle-school advisor on board to talk about the opportunities this education provides. These kids are learning lifelong skills that can help them in other fields, provide them with income and allow them to take care of their homes.”