2019年7月28日
Scientists have detected dozens of potential Mars quakes — and the early data suggests Mars may be less Earth-like
Scientists have been listening to whispers from below Mars’ surface. NASA’s InSight lander, which touched down on Mars in November 2018, gave scientists the unprecedented ability to detect and monitor quakes on Mars. The lander’s built-in seismometer detected its first quake in April, and since then, researchers have recorded dozens more potential Mars quakes.
So far, the biggest surprise is that seismic waves on Mars more closely resemble moon quakes than earthquakes – which probably means Mars’ crust is more dry and broken up than we thought.
“So far, we have assumed that the crust of Mars is similar to the Earth’s crust,” Simon Stähler, a Mars seismology researcher at ETH Zurich, said in a press release. “The fact that the wave form of the Mars quakes resembles the moon quakes gives us for the first time a picture of how the Martian crust is internally structured. Until now, we could only look at it from the outside.”
Not all quakes are created equal. When the Earth shakes, it’s because tectonic plates in the crust are clashing at fault lines. Mars doesn’t have tectonic plates, though. So scientists think Mars quakes probably come from a constant internal-cooling process, which happens inside most rocky planets. As the core cools, the material contracts, which causes stress to build. This eventually cracks the crust and causes a quake.
Seismic waves from quakes – regardless of the cause – also travel on different paths and at different rates, depending on what type of material they’re moving through. “A moon quake builds up for minutes, then decays away for an hour or more. So it looks very different,” Panning said. “The reason moonquakes look that way is because the moon’s surface is really dry and really broken up. It’s been basically sitting there for billions of years and getting hit by meteorites.”
A few dozen Mars quakes aren’t enough to reveal the red planet’s secrets, however.
“The biggest thing that we can do with the pretty small number of events we’ve seen so far is really understand how active Mars is now,” Panning said. “That’s telling you a lot of information on how Mars is evolving over time.”
Here's how to know exactly how much money you need in your emergency fund
Whether it’s because wages are low, debt repayment consumes our paychecks, or we’re overspending, nearly 60% of Americans have less than $US1,000 saved, according to a GoBankingRates survey. Most of that group has $US0. Before aggressively saving for retirement or investing, the very best thing you can do for yourself is build up a cash reserve.
An emergency fund is money you can access quickly if there’s a sudden medical emergency, your car needs a new transmission, you lose your job, or some other huge, unexpected bill lands in your mailbox.
If you’re looking for a savings benchmark, it will depend on your monthly expenses and the stability of your income. The Certified Financial Planner Board of Standards teaches the following rules of thumb:
If you’re a single-earner household, you need a minimum of six months worth of expenses saved.
If you’re a double-earner household, you need a minimum of three months worth of expenses saved.
If you’re a single-earner household with a second source of sizable income, you need a minimum of three months worth of expenses saved.
I basically started to treat my savings an expense and set up direct deposits from my paycheck into a high-yield savings account at a different bank than where I keep my checking account to avoid the temptation to dip into it for a non-emergency. Saving off the top meant I never had to contemplate what I was going to cut out in order to save more. The beauty of utilising a high-yield savings account for your emergency fund is that your money earns interest while it’s sitting there. Robo-advisers Wealthfront and Bettermenthave no-fee, high-yield accounts that earn some of the highest rates on the market right now. Interest can add a little boost to your savings – the more you put into the account, the more you’ll earn in interest. And most importantly, your money will be right there when you need it.
6 money apps and strategies to help you make a budget — and keep it
No matter how much money you earn every month, you’ll wind up with nothing if you spend it all. That’s why individuals and couples at all income levels track their spending. Here are some of the best money apps and strategies to consider as you get started.
Zero-sum budgeting: requires you to give each dollar you earn “a job,” whether that means allocating it towards a bill or saving it for the future. The goal of zero-sum budgeting is “spending” all the money you earn on paper each month, which includes allocating funds for debt repayment, savings, and retirement.
YNAB: also known as You Need a Budget. This app syncs with your bank accounts and helps you create a zero-sum budget and spending plan while doing all the grunt work and tracking for you. With YNAB, you can check in with your spending in real time, set debt-repayment goals, and allocate your money where it will help the most using your computer or mobile phone.
Mint: This budgeting app helps you track your spending with the use of charts and graphs so you can understand where your money goes each month. Mint also automatically updates and categorizes your purchases so you can check in at any time to see how your spending is going – and where you may need to cut back.
PocketGuard: lets you link your credit cards, bank accounts, investments, and loans in one place. The app updates and categorizes your transactions as you make them so you can see how much you’ve spent in categories like food and entertainment at any time.
Honeyfi: This app is geared to couples who want to manage their money and budget together, and its features help you do just that in a collaborative way.
Mvelopes: lets you create a budget, track your spending, and see your entire financial picture all in one place. This app focuses on the idea of creating separate spending buckets, or “envelopes,” for all your fixed and fluctuating expenses with the goal of helping you save more money and pay down debt faster. Mvelopes has three different plans to choose from. The basic plan costs $US4 per month and includes basic budgeting and expense tracking tools, while Mvelopes Plus costs $US19 per month and includes special financial and debt reduction tools along with a quarterly check-in with a budgeting coach.
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