I have invariably painted astronomers as saintly souls totally dedicated to the quest for knowledge, and for the most part, I’ll stand by that statement.

However, scientists are human. And like the rest of us, they are subject to the usual human foibles.

They live in an environment that is increasingly hostile, especially when they discover previously hidden patterns in nature that we don’t particularly want to hear. They are often the bearers of bad news, which is especially difficult when it involves major modifications in our lifestyle and behavior.

These days, global warming and climate change are prime examples. If you are a coal miner in the Appalachians, you don’t want to hear that your livelihood must disappear for the sake of the planet.

The rush to be first has its origin in a more fundamental problem. Funding for all but the most critical medical research is shrinking, and federal funding on climate change, for example, may soon disappear entirely.

Sometimes scientists are flat-out wrong or they simply seem like they can’t make up their minds. The simple egg became for a time the bearer of deadly cholesterol but soon was elevated to the status of “superfood.”

And sometimes they let their prejudices determine their results and even fake data to support their preconceptions. The researcher who “discovered” a link between childhood vaccines and autism has admitted that he faked his results and has repudiated his claim. However, the belief persists in some circles and simply won’t go away.

And occasionally, let’s face it, scientists unleash horrors upon the world. The first nuclear weapons dropped on Japan were the result of dedicated work by American scientists, but we have lived under that sword of Damocles ever since.

Still, most of their foibles seem relatively harmless. Scientists are sometimes consumed by professional jealousy. As a result, they sometimes rush to the news media before their results have been subjected to peer review, but matters sort themselves out eventually.

Such difficulties are not new. Over the centuries, professional jealousies have delayed more than a few significance scientific discoveries. In one case, our eventual understanding of the size and structure of the universe hinged upon a seemingly innocuous study of the moons of Jupiter.

Let’s take a look. Bright Jupiter is easily visible in the southeastern sky right now as a brilliant point of light. Binoculars will reveal its four brightest moons, the Galilean satellites, lined up around the planet.

As I did so recently, I was reminded that among the ranks of famous scientists, one can find a few grade-A sleazeballs.

Among the great accomplishments of Giovanni Cassini was the discovery of a large break in the rings of Saturn, a gap we still call Cassini’s Division. But Cassini was prone to raging fits of jealousy that ruined more than one promising scientific career.

In 1669 he was invited by the King of France to be the first director of the Paris Observatory.

As a boss, Cassini left a lot to be desired. Living accommodations at the observatory were spartan. One of Cassini’s assistants spent his nights sleeping on a windowsill.

Another assistant, Jean Richter, helped Cassini to measure accurately for the first time the distance between the Earth and the sun, giving Richter a certain measure of fame. Cassini sent him to a remote province to design military fortifications. So much for Richter’s career in astronomy.

Cassini’s greatest anger was reserved for Danish assistant Ole Roemer. Over the years, Cassini had plotted the orbits of the four main moons of Jupiter. Periodically, the moons pass behind Jupiter and are eclipsed by it. Once he knew the time each moon took to travel around Jupiter, Cassini should have been able to predict when each moon should pass behind the planet. But mysteriously, the intervals between eclipses weren’t always the same.

Roemer studied Cassini’s data and noticed that when the Earth and Jupiter were far apart, the times between eclipses were longer. Six months later, when the Earth was on the other side of the sun and closer to Jupiter, the intervals got shorter.

Roemer realized that the light from Jupiter’s moons simply had to travel farther when the Earth and Jupiter were farther apart. That meant that the light took time to get where it was going.

That contradicted what most scientists believed about light. They assumed that light got where it was going instantaneously. Galileo had tried to measure the speed of light with signal lanterns set at varying distances from each other. He had failed because the lanterns were much too close to measure differences. (Light can travel more than seven times around the earth in one second.)

Roemer noticed the difference because his “lanterns” were hundreds of millions of miles apart. From the data, Roemer was able to calculate the speed of light with amazing accuracy. It is his lasting contribution to science.

Cassini, however, was incensed and refused to accept the results. By 1681, Roemer was so disgusted that he returned to Denmark.

Cassini made many important astronomical discoveries before his death in 1712, and despite his obnoxious personality, he certainly deserves the praise that history gives him.

But Roemer deserves to be more than a footnote in astronomy books. His calculation of the speed of light was the first in a long series of discoveries that led almost 250 years later to Einstein’s theory of relativity, which has at its linchpin the constancy of the speed of light.

For astronomers, light’s constant velocity makes it possible to measure enormous distances, which are often expressed in multiples of the light year, the distance that light travels in one year. The number is difficult to comprehend in miles. One light year is about six trillion of them.

I recently got a glance at a galaxy near Jupiter right now. M87, as it is called is 65 million light years away. As the light entering my eyes at that moment left the stars of that galaxy, dinosaurs were disappearing from Earth.

I owe my understanding of the size and structure of the universe to Ole Roemer and the moons of Jupiter — as do we all.