Asteroid discovered with shortest orbit yet
Astronomers have discovered an asteroid that circles the Sun with the shortest orbit yet found, flying mostly inside the orbit of Mercury.
The illustration to the right shows the asteroids orbit, which is also tilted 32 degrees from the plane of the solar system.
The orbit of the approximately 1-kilometer-diameter asteroid takes it as close as 20 million kilometers (12 million miles or 0.13 au), from the Sun every 113 days. Asteroid 2021 PH27, revealed in images acquired during twilight, also has the smallest mean distance (semi-major axis) of any known asteroid in our Solar System — only Mercury has a shorter period and smaller semi-major axis. The asteroid is so close to the Sun’s massive gravitational field, it experiences the largest general relativistic effects of any known Solar System object.
Relatively few asteroids have been found with orbits shorter than Earth’s, because to find them astronomers have to turn their telescopes sunward, where viewing is limited to the early evening or early morning. Few space-based telescopes in all wavelengths also don’t look this way much, because of the risk of damage from the intense sunlight.
It is thus unknown exactly how many asteroids exist with similar orbits. There may be many, with many having short eccentric orbits, similar to comets, that extend out to Earth’s orbit and thus pose a risk. Or there may be few, since such orbits so close to the Sun are likely to cause the asteroid’s break-up and destruction over time.
Knowing how many of course is important, in order to obtain a full census of those asteroids in the solar system that might hit the Earth. To get it will likely require placing a probe designed to look for them.
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Astronomers have discovered an asteroid that circles the Sun with the shortest orbit yet found, flying mostly inside the orbit of Mercury.
The illustration to the right shows the asteroids orbit, which is also tilted 32 degrees from the plane of the solar system.
The orbit of the approximately 1-kilometer-diameter asteroid takes it as close as 20 million kilometers (12 million miles or 0.13 au), from the Sun every 113 days. Asteroid 2021 PH27, revealed in images acquired during twilight, also has the smallest mean distance (semi-major axis) of any known asteroid in our Solar System — only Mercury has a shorter period and smaller semi-major axis. The asteroid is so close to the Sun’s massive gravitational field, it experiences the largest general relativistic effects of any known Solar System object.
Relatively few asteroids have been found with orbits shorter than Earth’s, because to find them astronomers have to turn their telescopes sunward, where viewing is limited to the early evening or early morning. Few space-based telescopes in all wavelengths also don’t look this way much, because of the risk of damage from the intense sunlight.
It is thus unknown exactly how many asteroids exist with similar orbits. There may be many, with many having short eccentric orbits, similar to comets, that extend out to Earth’s orbit and thus pose a risk. Or there may be few, since such orbits so close to the Sun are likely to cause the asteroid’s break-up and destruction over time.
Knowing how many of course is important, in order to obtain a full census of those asteroids in the solar system that might hit the Earth. To get it will likely require placing a probe designed to look for them.
In order to remain completely independent and honest in my writing, I accept no sponsorships from big space companies or any political organizations. Nor do I depend on ads.
Instead, I rely entirely on the generosity of readers to keep Behind the Black running. You can either make a one time donation for whatever amount you wish, or you sign up for a monthly subscription ranging from $2 to $15 through Paypal, or $3 to $50 through Patreon, or any amount through Zelle.
The best method to donate or subscribe is by using Zelle through your internet bank account, since it charges no fees to you or I. You will need to give my name and email address (found at the bottom of the "About" page). What you donate is what I get.
To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
For PayPal click one of the following buttons:
If these electronic payment methods don't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
I wonder if it’s a “pile of rubble”, or a large chunk of rock? perfect for an observational satellite to shadow!
The astroid protecting the satellite from the suns radiation and static interference, so it can perform its science mission, launching small probes, while searching the inner solar system for more astroids?
Every new discovery comes with it new possibilities…
Knowing how many of course is important, in order to obtain a full census of those asteroids in the solar system that might hit the Earth. To get it will likely require placing a probe designed to look for them.
The NEO Surveyor is already under development.
Call it Vulcan…a solar furnace. Eat out the back and focus a beam out the tailpipe.