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Mars from Hubble

There's a meme that goes around periodically on Facebook showing Mars, only sized to look as large as the Moon does from Earth. The meme(s) typically argue that when the Earth and Mars hit their smallest distances from one another, Mars will be not merely visible to the naked middle equally usual, merely the same apparent size as the Moon. I've always thought these sorts of messages must drive astronomers and scientists absolutely insane, given that the only mode Mars would ever wait that big from Earth is if every single person living on practiced ol' Sol Iii is nigh to have a actually, really bad day.

Mars-Moon

It turns out astronomers also make these kind of mistakes. In an excited cannonball to the Astronomer's Telegram, Peter Dunsby reported the detection:

[A] very brilliant optical transient in the region between the Lagoon and Trifid Nebulae based on observations obtained from Cape Town on 20 March 2022, between 01:00 and 03:45 UT. The object was visible throughout the full duration of the observations and non seen when this field was observed previously (08 March 2022). The optical transients is at least first magnitude and is located at the following coordinates: RA (2000): 18h 04m 50s Declination (2000.0): -23d 29m 58s The coordinates are authentic to a few arcseconds. There is no obvious analogue at this position on the Digital Sky Survey plates. Observations were obtained using an 80mm refractor. The attached URL show the image of this field (two.3 x one.vii degrees, plate scale of 9 arcseconds per pixel) on 20 March 2022. The optical transient is the brightest star in the field. Farther observations are strongly encouraged to establish the nature of this very bright optical transient.

40 minutes later — undoubtedly a rather long twoscore minutes, with some alternating between excitement and then a growing sense of despair — Dunsby posted a follow-upwardly bulletin. In a missive titled "Erratum to ATel #11448," he notes: "The object reported in ATel 11448 has been identified as Mars. Our sincere apologies for the earlier study and the inconvenience caused."

While embarrassing for Mr. Dunsby, this is scarcely the outset time objects in the solar organisation have been either misidentified or mistakenly idea to exist. Dwarf planets like Ceres (the first asteroid to be discovered) were originally thought to exist planets; Ceres is the merely asteroid known to be rounded by its own gravity. Astronomers knew for years that gravitational disturbances in the orbits of Uranus and Neptune could signal the beingness of another planet, merely this world, Planet X, was hypothesized to exist much larger than the dwarf planet, Pluto, that nosotros eventually establish. A hypothetical Planet V between Mars and Jupiter was once theorized besides, with the asteroid belt every bit the sole remaining evidence of this planet'due south existence; this is at present idea to exist unlikely given the size and distribution of the asteroid belt. Other planets, like Vulcan, a hypothetical planet even closer to the sun than Mercury, were likewise in one case expected to exist.

Of course, none of these is quite the same every bit misidentifying Mars, a planet that's been known to humanity since ~2000 BC. What can we say? At least Dunsby didn't make a meme.