Tag Archives: planet

Smallest spherical planet so far found

Hygiea

A new image of the asteroid Hygiea has revealed that this main belt object is actually spherical, making it the smallest spherical asteroid so far discovered and suggesting that it could be defined as a planet.

The image, taken by the Very Large Telescope (VLT) in Chile, is to the right. The asteroid was first discovered in 1849 and is the fourth largest in the asteroid belt, after Ceres, Pallas, and Vesta, with a diameter of 267 miles.

The image once again challenges the definition of what makes a planet. It also makes difficult the vague term “dwarf planet.” At what point does a dwarf become a full planet? This has never been clarified, which is why I tend to avoid using the term dwarf planet.

In my many interviews of planetary scientists, they generally dismiss the IAU’s poor definition of a planet and define a planet as anything that has settled into a spherical shape. In the case of Hygiea, that seems to apply.

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Russia to launch a dozen cubesats for Planet

Capitalism in space: Planet has signed a deal with the Russian government entity that bundles smallsat secondary payloads to launch a dozen cubesats on a Soyuz rocket presently scheduled to launch later this year.

This agreement provides further evidence that the cubesat commercial industry is here to stay. There are a lot of these contracts right now (India is scheduled to launch 30 tomorrow). The need for more small rockets to launch such satellites appears almost overwhelming, and thus a good financial choice.

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Rocket Lab gets new launch contract

The competition heats up: Rocket Lab has signed a three launch contract with the smallsat Earth resources satellite company Planet (formerly Planet Labs).

The contract covers three dedicated launches of Dove satellites built by San Francisco-based Planet, formerly known as Planet Labs, on Electron vehicles. The companies did not announce terms of the deal, although Rocket Lab quotes a list price of $4.9 million per Electron launch on its website.

Mike Safyan, director of launch and regulatory affairs for Planet, said in an interview during the International Space Station Research and Development Conference here that the number of satellites that each launch will carry is still being determined, but will likely be between 20 and 25. Each Dove is a three-unit cubesat with a mass of about five kilograms.

If this report as well as previous ones are correct, the first Electron rocket launch will happen before the end of this year.

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Alan Stern gives the IAU a piece of his mind

New Horizons’ principle investigator yesterday told the International Astronomical Union what he thinks of their definition of a planet:

“It’s bulls—,” he told Tech Insider (and said we could quote him on that).

The problem, Stern said, is that the reclassification largely stemmed from the opinions of astronomers, not planetary scientists. His beef here is that astronomers study a large variety of celestial objects and cosmic phenomena, while planetary scientists focus solely on planets, moons, and planetary systems.

“Why would you listen to an astronomer about a planet?” Stern said. He compared it to going to a podiatrist for brain surgery instead of a brain surgeon. “Even though they’re both doctors, they have different expertise,” Stern said. “You really should listen to planetary scientists that know something about this subject. When we look at an object like Pluto, we don’t know what else to call it.”

Stern’s opinion is not unique among planetary scientists. I have interviewed many, and read reports by others, which consistently say that they object strongly to the IAU’s definition. To them, if a object has enough mass to force it into a sphercial shape, it is a planet.

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