Okay, not just one. It starts with lots of pebbles — a flat sea of them stretching perhaps hundreds of times wider than the distance from Earth to the sun. Their sizes vary greatly. Some may be mere dust particles. Others may be small to fairly substantial rocks.
Like fussy chefs in a kitchen, astronomers today debate over how much of which ingredients must have been present in that early solar system. And when. And how they might have interacted and combined. And what would happen if you changed their temperature.
How shrinking planets might explain missing planets
Astrophysicist Trevor David of the Flatiron Institute led the new research. It was published in the peer-reviewed Astronomical Journal on May 14, 2021.
Astronomers noticed the so-called radius gap in exoplanets in 2017. Many planets are either smaller than 1.5 times Earth’s radius. Many are larger than two times Earth’s radius. But few are in between. Astronomers wanted to know why.
Trevor David and colleagues took a new approach to the problem of the radius gap. They wondered if it changes with planets as they age.
Skywatch: Catch a close pairing of the innermost planets | Outdoors | magicvalley.com
If Earth were motionless, Mercury and Venus would therefore meet up in our sky every 145 days. From the orbiting earth, the average time between Mercury-Venus conjunctions is longer than 145 days, and the interval varies considerably.
Mercury's maximum angle from the sun is 28 degrees, while Venus ranges up to 47 degrees. So, whenever Venus is more than 28 degrees from the sun, a Mercury-Venus conjunction is impossible.
Venus spends around 234 days within 28 degrees of the sun when it's on the far side of its orbit, but only 38 days when on the near side. Earth and Venus return to the same relative positions every 584 days, so Venus is in position to meet up with Mercury a little less than half the time.
Deep oceans dissolve the rocky shell of water-ice planets | EurekAlert! Science News
IMAGE: Cut-away diagram of a water-rich sub-Neptune exo-planet highlighting, in orange color, the interaction region between a deep H2O layer and the underlying rocky mantle view more
What is happening deep beneath the surface of ice planets? Is there liquid water, and if so, how does it interact with the planetary rocky "seafloor"? New experiments show that on water-ice planets between the size of our Earth and up to six times this size, water selectively leaches magnesium from typical rock minerals.
Helium Rain is Possible inside Jovian Planets, New Experiments Suggest | Planetary Science, Space
Jupiter, Saturn and numerous giant exoplanets discovered to date consist mostly of hydrogen and helium. In 1977, planetary scientists predicted the existence of helium rain layer inside such planets. However, achieving the experimental conditions necessary to validate this hypothesis hasn't been possible — until now.
An artist's impression of the ultra-short-period sub-Neptune exoplanet TOI-1634b. Image credit: Sci-News.com.
"This is important to help planetary scientists decipher how these planets formed and evolved, which is critical to understanding how the Solar System formed."
Mercury and Venus will be at their closest until 2033 tonight, but may be hard to spot | Space
If you're up for an observing challenge, Venus and Mercury will meet in the night sky Friday (May 28) for their closest encounter until Nov. 5, 2033.
The pair of planets will be visible low in the western sky for roughly 30 to 40 minutes after sunset, according to EarthSky . Observing will be tough given you may be competing with buildings and air pollution to see the planets, so bring binoculars if you can.
Sky & Telescope suggests looking west-northwest and starting with the bright stars Pollux and Castor, which are the heads of the Gemini constellation "twins." Slightly below Pollux and to your left, assuming you're gazing with the naked eye, you'll see Mars.
What Planets Are Retrograde June 2021? An Astrologer Explains
Oh dear, it's another dreaded retrograde season. Is this when all of your exes come back from the past like a zombie relationship apocalypse? Does it cause your computer to crash and sizzle with smoke, erasing every document you've ever written? To put your mind at ease, no (at least, probably not). Retrogrades tend to attract way more fear than truly necessary, but that doesn't mean they don't incite drama and complications.
This month actually involves quite a few retrogrades — five to be exact. Not all of them will induce the same level of intensity and confusion, though. Retrogrades actually mean something different for each planet in astrology, and it's important to make that distinction.
WPIAL lacrosse championships: Mars surge lifts Planets to 2A title | Pittsburgh Post-Gazette
Mass Effect's Cut Planets & Missions Being Modded Into Legendary Edition
Modders are adding cut content into Mass Effect Legendary Edition that will restore missions and planets left out in the original trilogy. Mass Effect modders had updated or debugged the series long before Legendary Edition was released. Now with the remastered games out, modders are combing over the files for even more content to add. The newly uncovered files, previously unusable due to technological limitations, can now be implemented with modern modding tools.
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