Space, in brief

Astronomers found 84 objects of a kind never catalogued, in six galaxies, using pictures already sitting in the public archive of Chandra, NASA's X-ray telescope. [1]

nobody has yet caught one of these stars before it explodes [2]

Chandra's public archive held these 84 objects for years.

X-ray telescopes are built to catch high-energy light, and these objects give off almost none of it, so they sat in the pictures as faint dots nobody had sorted out.

Mustafa Muhibullah's team at the University of Alabama found them by keeping only the dots that show up in Chandra's lowest-energy pictures and vanish in the higher-energy ones. [1]

The words 'mysterious' and 'unlike any they have seen before' make a signal nobody has explained feel like something that has just arrived in the sky, when the objects were in the pictures all along and what is new is the sorting. [1][2]

A new class of object, named by them, out of pictures already in a public archive; no new telescope time was needed. [1]

A 27-year-old telescope has just produced a new class of object from its archive.

They still do not know which stars produce their measuring stick. Jimmy Irwin said they study the explosions only after they have happened. [2]

What the 84 objects actually are.

The team says they most likely involve a black hole, neutron star or white dwarf pulling gas off a companion star, but has not identified a single one. [1]

Whether any exist in the Milky Way.

None has been found in our own galaxy. The team's explanation is that we look through the Milky Way's own gas, which soaks up ultraviolet light, so a nearby one would be hidden by the same effect that hid all 84. [2]

Whether these objects are what strips electrons from the gas between stars.

Hot massive stars are not numerous enough to explain all of it, and the team offers the new objects as a possible answer, not a measured one. [2]

Whether any of them will explode as a Type Ia supernova.

Astronomers have searched for the stars that become these explosions for years without finding one. The team says these objects could be candidates and no more. [1][2]

Eighty-four objects of a kind nobody had catalogued were found this week in pictures that had been sitting in Chandra's public archive, open to anyone.

What a telescope cannot see looks like empty sky

A telescope is built to catch one range of light

Whatever shines mostly outside that range leaves a faint mark, or none

The catalogue fills up with what the telescope sees well

In that catalogue, empty sky and an unseen object look the same

A new band, or a comparison between bands, turns the blanks into objects

Nothing was hiding these 84 objects except the choice of which light to look in. They appeared the moment the team compared Chandra's low-energy pictures with its high-energy ones.

A new band shows what the old one missed and leaves out other things in turn.

Everyone reads the world through some instrument: a telescope, a survey, a news feed, their own two eyes. Each one leaves blanks that look like empty space.

Santos-Sanz said the decade of ground-based records, some from back gardens, is what let the team recognise that Webb's reading was unusual. [3]

The first predicted occultation observed from Webb worked despite a last-minute course correction, and the method was reused on Quaoar. [3]

The next reading needs another star to pass behind the rings as seen from Webb, and the team cannot schedule that. [3]

Whether Chariklo's rings really changed.

The Webb team measured a clear difference from earlier ground-based records. But the rings could be lumpy, so a different slice was measured, or they could look different in infrared than in visible light. Pablo Santos-Sanz says going from the measurement to a cause is much harder. [3]

What is moving material between Chariklo's two rings.

Mass passing from the outer ring to the inner one, or an unseen moon shepherding the inner ring, are the two ideas. Only a future occultation can test either, and those happen when the geometry allows, not when astronomers choose. [3]

Webb's first predicted stellar occultation worked, and the same set-up has since been used to study the rings of Quaoar, a dwarf planet in the Kuiper belt.

The change in Chariklo's rings could only be recognised because amateur astronomers had been recording occultations of it for the past decade.

Apollo never landed at the south pole, so its shadows, dust and micrometeorites are blanks in the record. Phase one exists to fill them in before anyone builds there.

Phase one of the Moon Base is described as more than twenty landings bought from several vendors, and NASA's events list names their landers under the Moon Base and CLPS labels. [4][6]

Garcia-Galan says habitats must sit at least a mile from the landing site because landing engines blast the ground, so every crew begins with a drive across the pole in a vehicle sent ahead. [4]

NASA's programme manager puts the start of permanent hardware in 2028 or 2029, after a learning phase whose landings have not begun. [4]

When the Moon Base's first robotic landing flies.

Carlos Garcia-Galan said in August that he hoped for one landing this year and several next year. NASA's own events list names the landers under Moon Base and CLPS labels. [4][6]

How long the shadows at the lunar south pole actually last.

Garcia-Galan said it may be several days but not fourteen. Phase one is meant to measure it, because Apollo landed elsewhere. [4]