If you believed some of the commentary taking place over Standard & Poor’s decision to reduce the U.S. bond rating from AAA to AA+, you would think that astronomers had just detected a killer asteroid that would destroy all life on Earth.

In truth, the decision by one rating agency (which the two other major rating agencies, Moody’s and Fitch, have declined to join) has changed nothing about the nation’s underlying ability to pay its debts on time.

That ability remains as strong as ever. Even assuming a worst-case scenario, in which Congress failed to come up with a proposal last week to raise the debt limit, federal revenues remain sufficient to pay all the interest on our debt as well as fully fund programs such as Social Security, Medicaid and Medicare.

There need not have been any “default” even if the Aug. 2 “deadline” had been pushed off a few days, as has often happened in the past.

Those concerned should ponder these facts: First, S&P specifically said it was not making any judgment about the relative merits of tax hikes and spending cuts.

Rather, it was the inability of Congress to reach an agreement about the debt burden that caused the agency to issue its cautionary downgrade, which has now been extended to federally linked mortgage giants Fannie Mae and Freddy Mac and a near-dozen federal depository institutions.

Second, the need for such a caution remains in dispute. S&P, remember, is one of the rating agencies that continued to award strong ratings to financial institutions and investment vehicles based on exaggerated mortage values that ended up by bursting the “housing bubble” in 2009-10.

Why we should think this rating is any better thought-out is a mystery, particularly as it does not represent the consensus in its field.

It is also problematic why President Obama waited until Monday afternoon to try to calm the markets down. He should have spoken out early in the weekend, offering solid assurances that the situation was under control, so that the world’s markets would not have opened Monday morning without any inkling of what he was thinking.

Obama’s statement, while making some needed points – including the fact that “this remains a AAA nation” – was couched in general terms and was clearly intended as a general reassurance rather than a statement of specific fiscal goals, which might have offered a greater calming effect.

There’s time for specifics to be generated, of course, and much depends on what the 12-member congressional “super committee” comes up with for a longer-range fiscal solution.

Unfortunately, at least in the short run, investors here and abroad seem unwilling to wait – and are harming their own interests as much as their nations’. The situation is just not that dire because, despite its politicians’ problems, the U.S. remains one of the world’s strongest economies. The two issues should not be confused.