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Starlight
- A better measurement that made the model worse
- A brightness is a distance only if something is known
- A continuum that was never observed
- A diameter that depends on a model atmosphere
- A field strength read off a line that will not split
- A luminosity class is a density measurement
- A magnitude has to say which light
- A magnitude in a band the source never had
- A magnitude measured where nothing was measured
- A mean dominated by the gaps
- A minimum that was mistaken for a principle
- An angle of five hundredths of an arcsecond
- An instrument more polarised than the sky
- A period found in the gaps
- A phase that survives what corrupts it
- A response measured pixel by pixel
- A sample brighter than the population it came from
- A scale that runs backwards, multiplies, and works
- A shift in a line is a speedometer, and it works at any distance
- A slope that needs no source
- A spectrum with no continuum left in it
- A spectrum with no temperature in it
- A speed read off an edge
- A temperature and a gravity that trade against each other
- A temperature that depends on where the observer stands
- A velocity that is an average of lines that disagree
- Colour is a thermometer, and it reads across the galaxy
- Composition, read from what is missing
- Dust makes everything look further away
- Every distance is measured with the last one
- How much of a line is not in its depth
- Resolution without a mirror
- The circulation that should have stirred every fast rotator
- The continuum is made by one atom in ten thousand
- The depth is not the area
- The direction a photon count throws away
- The distance is not one over the parallax
- The dust is not lost light, it is moved light
- The error bar that comes from counting
- The faint star is measured against a brighter sky
- The light that is missing from the edge
- The metre per second that is not the star
- The pole-on stars a brightness limit prefers
- The same star through two telescopes
- The same width for three different reasons
- The second thing a spectrum says
- The surface that is a depth
- The tallest peak in nothing at all
- The triangle that reaches the stars, and stops
- Two instruments blind in opposite directions
- Why hydrogen's lines are strongest where hydrogen is not
- The classical law gives every star one colour
- Three shifts larger than the error bar, and two that cancel
- Two laws that are one curve read twice
- The best aperture throws away a tenth
- The comparison stars are part of the measurement
Galaxies
- A birth rate measured from light nothing young emitted
- A bridge and a tail drawn by one force
- A cloud that cannot become a star
- A cluster weighed three ways
- A count with a knee in it
- A direction measured by something with no strength in it
- A disc held open by what cannot be photographed
- A disc that turns slower than its mass requires
- A disc the size its halo was born with
- A dispersion inflated by orbits nobody resolved
- A distance measured with a stopwatch
- A flare that puts a ceiling on a mass
- A galaxy held up by disorder
- A galaxy measured from inside it
- A histogram that says the box was not closed
- A hole that says mass times time
- A line width that is a distance
- An argument about the innermost kiloparsec
- An arm that cannot be made of stars
- An arm that is undone by the work it does
- A one-per-cent distortion, and a million galaxies to see it
- A rotation curve that refuses to fall
- A sheet of mass that changes nothing but the answer
- A size measured from a delay
- A stream is not the orbit it came from
- One velocity and two distances
- Red, gas-poor, and still spiral-shaped
- Support that cannot be squeezed away
- The baryons that are not in the galaxies
- The brightness distance cannot touch
- The cloud that cannot hold itself up
- The debris that returns fastest lights up last
- The energy at which a sky begins to point
- The factor that multiplies every quasar mass
- The gas runs out before the galaxy does
- The last parsec, and the stars that are not there
- The line a star is swallowed at is not the horizon
- The mass at the centre that is not stars
- The mass that is not the light
- The same curve, two galaxies
- The speed a line width stands in for
- The stars a black hole eats come from a narrow band
- The support and the seed are the same motions
- Three mass models that fit the same curve
- Two colours, and almost nothing between
- Two geometries and one bit to choose between them
- Two parameters that lensing measures as one
- Two temperatures, and nothing in between
- Weighed by the light that bends past it
- Where a pattern is allowed to turn
- Whether it merges is a ratio of two times
- The count theory predicts, and the inference it costs
- Two counts that are not the same shape
- The same census, taken in two places
- The metals a galaxy keeps measure what it threw away
- A gradient the old stars have walked away from
- The iron clock has no single delay
Cosmology
- A blur that measures a depth
- A budget whose familiar part is five per cent
- A coincidence that is a factor of fourteen
- A constant that is an angle divided by a length
- A dipole a hundred times the signal
- A factor of three, and the flatness that prices every cure
- A forest with no continuum left
- A horizon three times larger than the age allows
- A length in centimetres, measured against an angle
- A map stretched by the thing it measures
- A map that is not of positions
- A mass measured by what it stopped from forming
- An abundance with no direction to correct in
- An amplitude and a depth that arrive multiplied
- An expansion that was supposed to be slowing
- An orbit feels the acceleration and never the rate
- A particle count taken from a dwarf galaxy
- A ratio that is an energy and a distance
- A redshift that changes while it is watched
- A residual that is somebody else's velocity
- A ruler measured along and across
- A shadow that does not get fainter with distance
- A standing wave frozen at one instant
- A test that can only fail one way
- A trough that proves the forest survived
- Four abundances and one free parameter
- Four distances to the same galaxy
- Half the ordinary matter was missing, and a millisecond found it
- Homogeneous above a hundred megaparsecs
- It ends when the walls meet
- One number that is an age, a size and a density
- Spin acquired before there was anything to spin
- The age of the universe weighs the Local Group
- The clock on which light travels in straight lines
- The epoch nobody saw moves the tilt
- The galaxies that are already out of reach
- The most perfect blackbody ever measured
- The number that would say whether it is a constant
- The residue that failed to burn
- The same constant, measured twice, five sigma apart
- The same ruler measured twice, ten billion years apart
- The seed that cannot be remembered
- The shift that is not a Doppler shift
- The Sun's speed counted in quasars comes out twice too large
- The surface the background actually is
- The tilt knows the slope and not the height
- The universe that was lumpy at one second
- Two coincidences with one mechanism
- Two horizons that differ only in who is inside
- Whether there is a horizon at all
- Why the sky is dark
- The darkness has a number in it
- A background weighed by what it stops
- Two skies where the paradox comes out right
- A velocity that has the colour of the sky
- Too few clusters, or a scale that reads light
- A null that moves with the temperature
Spaceflight
- A boom held upright by a difference in gravity
- A burn that moves the wrong way
- A coefficient that belongs to the surface, not the satellite
- A collision rate that needs no collision
- A density model wrong by a factor of two
- A manoeuvre that has never been flown once
- A map of the transfers that are free
- An angle measured against a quasar
- An ocean found in a Doppler residual
- An orbit that speeds up as it is slowed down
- A plane change paid at the worst speed there is
- A position measured from a frequency
- A rotation split between two burns
- A satellite that drifts to one of two longitudes
- A spin that left the axis it was given
- A stationary satellite that draws a figure of eight
- A swath is sized at the equator
- A tumble stopped by the field it tumbles through
- A weather forecast made out of orbits
- A wingnut that turns over on its own
- Catching up by slowing down, which cost Gemini 4 its fuel
- Five satellites and not four
- Flying further away in order to turn
- Four media between the antenna and the spacecraft
- Going too far in order to arrive cheaply
- One trajectory, stitched from three two-body problems
- Stealing speed from a planet, which does not notice
- The cheapest place to turn
- The cheapest way between two orbits, and why it is so slow
- The circle a station can see
- The discontinuity a patched conic hides
- The exponential that decides what can be flown
- The fragments nobody can see and cannot shield against
- The line under a satellite
- The orbit that has to be paid for every year
- The planet pays, and it shows
- The same burn is worth more when moving fast
- The same planet, three times
- The speed that does not come back, and the √2 that separates it
- The spin that has to be put somewhere
- The stage that has to be thrown away
- The transfer that costs more the gentler it is
- The window that comes back and the cost that does not
- Three clocks and nothing to fall onto
- Two dates decide a mission
- A corridor a degree and a half wide
- An equation that does not break at the speed of light
- Choosing a propellant is choosing a molecular weight
- Orbit costs 7.8 and a launch buys 9.4
- The split that is not an equal split
- The tube that leads out of a neck
- One square root that raises the orbit and turns it
- The engine is chosen by the calendar
- A drive with no rocket equation
- A fuel gauge that is worst when it is needed
- An unstable point that costs less to hold than a stable orbit
Sky
- A boundary that hardly moves
- A clock whose zero is moving
- A frame made of things that are not points
- A month that has to be tabulated
- An aurora that is a sixth root inside an arcsine
- An error budget added in quadrature
- An hour that stretched with the season
- A population counted by shadows that never repeat
- A right ascension is a date
- A second that depends on where the clock is
- A shape measured by the edge of a shadow
- A solar radius measured past a mountain range
- A star that blinked before it should have
- A Sun that stops and runs backwards
- A ten-metre mirror that resolves like a ten-centimetre one
- A tilt held still by being too fast to resonate
- A tilt that is not a constant
- A wobble that should have stopped
- A year that is not a whole number of days
- Each event pays for the prediction of the next
- Five numbers from one wiggle
- Four numbers that weigh a planet's core
- On Mars the orbit outweighs the tilt
- Ozone keeps the twilight zenith blue
- Phases are not shadows, and eclipses are
- Six kinds of second
- The air's height against the planet sets the twilight
- The atmosphere is a prism as well as a lens
- The brightest instant of an occultation is its middle
- The correction has to be faster than the air
- The day that is four minutes short
- The earliest sunset is not the shortest day
- The eclipse that repeats a third of a world away
- The edge of a shadow is a wave
- The face that is not quite fixed
- The flare that arrives from somewhere else
- The loop a planet does not make
- The other twenty arcseconds
- The pole star has a shelf life, and the sky has a slow hand
- The shadow that climbs the zenith
- The smallest term between a clock and the Sun
- The solar system measured from inside one orbit
- The sphere that is not there, and why it is still the right model
- The Sun is a bad clock, by up to sixteen minutes
- The Sun sets before it sets
- The Sun's path, and the tilt that makes the seasons
- The whole sky drifting towards one point
- The wobble inside the wobble
- Three definitions of night
- Two fictitious suns in sequence
- Where a star is depends on who is asking
- Five zones, and one angle
- The sunniest place is the summer pole
- The hottest month is not the sunniest
- A triangle of meetings that turns in eight centuries
- Brightest as a crescent, and not as a disc
- A right angle short by a seventh of a degree
Stars
- A brightness that would blow the star apart
- A clock read against a model of everything in between
- A clock that runs down and says what it is
- A clock that stops while its interior freezes
- A clock with no fuel in it
- A convective boundary with no theory to fix it
- A corner of the diagram that has to be earned
- A field that would have arrived ten thousand times too strong
- A floor under the centre that assumes nothing
- A fluid that turns as one piece
- A flux that is a thermometer to a tenth of a per cent
- A length nobody derived, fitted to one star
- A magnetic clock read off a butterfly
- A mass function corrected by an age
- An age read off a bend
- An equation of state is already a star
- A neutron star born turning too slowly
- An exponent that is a slope, not a law
- A radius that decides what matter can be
- A shear layer that should have spread
- A spectrum that is a stack of temperatures
- A star held up by a rule about counting
- A star is held up by its own weight
- A star that tells its distance by how slowly it blinks
- A surface that slowed because the star grew
- A threshold with no free parameter in it
- A wind that takes no mass and all the spin
- Every note turns back at its own depth
- Mass decides everything, by a power of three and a half
- Most stars are small, and most of the light is not
- One step of memory kept at the poles
- The candle that has to be standardised
- The clock that starts by forgetting
- The companion survives, and it is moving
- The darkness a field pays for
- The diagram that sorted the stars, by plotting two things against each other
- The disc that has to throw angular momentum away
- The explosion that never reaches the surface
- The exponent no pulsar has
- The flow that narrows its own channel
- The furnace that runs cooler than a compost heap
- The interior read from a comb of frequencies
- The main sequence is a place stars sit, not a track they travel
- The mass a cold star cannot exceed
- The mass a star does not keep
- The only stars whose masses are known
- The only thing that leaves the centre
- The part of a star that boils
- The part of a star that never slowed down
- The resonance that had to exist
- The star that swells because its centre shrank
- The valve that has to sit at the right depth
- The wake and the meal are one calculation
- Three causes with three shapes in one curve
- Three clocks and a runaway
- Two explosions told apart by a missing line
- Two orbits of one pair, and a distance falls out
- Two radii, from a light curve alone
- Two scaling relations calibrated on one star
- Two stars only a Fourier transform can tell apart
- Why the biggest stars die first, and take the galaxy with them
Exoplanets
- A centroid that moves when the brightness does not
- A chain that could not have been assembled in place
- A companion on the same orbit, seen in the planet's clock
- A composition that dates a formation rather than placing it
- A duration that measures an eccentricity
- A forecast that fails on a schedule
- A gap in a histogram that says how planets are built
- A light curve with a fold in it
- A mass that is only a mass once the eccentricity is known
- A misalignment only cool stars forget
- An asymmetry that the Earth's own orbit puts in
- An event of a few hours and no host
- A planet measured by the light it removes
- A planet radius is a stellar radius
- A planet ten times larger in one colour
- A planet that was the star's own rotation
- A planet where one cannot form
- A radius no cold planet is allowed
- A radius that depends on the colour it is measured in
- A shadow crossing a rotating line
- A smaller star puts the valley lower
- A spectrum flattened by cloud, or by nothing
- A star magnified by a planet nobody will see again
- A star subtracted using the star
- A torque that nearly cancels
- A transit late by the width of an orbit
- A velocity measured from a shape
- Capture is a direction, not a strength
- Every survey draws a different sky
- Four contact points, and what they fix
- A planet that is never confirmed, only validated
- Nine orders of magnitude, half an arcsecond apart
- One density, and every planet that has it
- One number sets the zone
- One timing curve and five planets that could draw it
- Planets found by a transit running late
- The band moves and the orbit does not
- The envelope that doubles a planet lasts longest
- The gas a planet cannot keep
- The line beyond which ice counts as rock
- The part of a rate that is a definition
- The planet is seen when it disappears
- The planets that were not seen
- There is not one line, there is a staircase
- The shield that is also a funnel
- The star moves, and the mass is a lower bound
- The stripping runs ahead of the starlight that drives it
- The young Sun's spin decides what the Earth kept
- Two elements in a ratio, and a birthplace read off it
- Two methods, and one density
- Two systems that draw the same curve
- The threshold that is not a threshold
- Every method prefers a circle, and not for the same reason
- How many planets a star has is not a measurement
- A thermostat that only halves the error
- A year too short to feel its own eccentricity
- Steam before the zone existed
Gravitation
- A cluster that boils itself away
- A core weighed by something that never went in
- A day five hours long
- A detector the size of the galaxy
- A distance tangled with an angle
- A distance with no ladder under it
- A drag computed with a logarithm nobody can pin down
- A drag that is strongest in the middle
- A drag with nothing to drag against
- A feeding zone, and the spacing it forces
- A heat flow that depends on a number nobody can compute
- A moon heated by not being allowed to relax
- An answer obtained along a path that was not taken
- An average that weighs what cannot be watched
- An edge is a balance, not a boundary
- An error that grows like a random walk
- An ocean is detected and its depth is not
- An orbit measured to be shrinking
- A pair that heats what is trying to cool
- A prediction with an expiry date
- A quality factor quoted without a period is half a number
- A ring weighed by the wave crossing it
- A rotation locked to the orbit, but not one to one
- A sphere pulls exactly like a point, and the proof is a pair of cones
- A spin that is one length in disguise
- A step that must not be adapted
- Every pair arrives circular
- Five places that keep station, in a problem with no solution
- Forty-three arcseconds, after everything else
- How long a system takes to forget
- How much a world gives
- Neither body is still, and the wobble is how planets are found
- Nothing in the sky is weighed in kilograms
- One heat flow, and two viscosities
- One number where two masses were
- Resonance clears a gap in one place and locks a moon in another
- The curve that says where a body cannot go
- The distance at which a moon stops holding together
- The Earth's shape, read off a satellite's node
- The field a satellite is allowed to feel
- The number that survives the encounter
- The part of a kick that heats nothing
- The part of a shape the spin cannot explain
- The period a star is pulled towards
- The region a planet may keep a moon in
- The second number a black hole has
- The surface a star stops at
- The system that gets hotter as it loses energy
- The tide is a difference, which is why there are two of them
- The tunnel that takes the same time from anywhere
- The weakest field changes the answer
- Three bodies, and what "no solution" actually means
- Two bodies replaced by one that does not exist
- Where the chaos comes from
- Whether the heavy material sank
- Wrong about where, and right about how much
Orbits
- A collision dated by a scatter plot
- A comet that arrives a day early
- A cut-off period that is an age
- A drift rate that says what the surface is made of
- A family whose size is a choice
- Aiming at a plane instead of at a planet
- An acceleration that was the spacecraft's own heat
- An average that precession cannot move
- An eccentricity that cannot be zero
- An error that is nearly all in one direction
- An inclination that turns into an eccentricity
- An invariant that is only almost one
- An orbit can look exactly like a circle and still not be one
- An orbit moved by heat
- A resonance with the planet itself
- A surface dated by counting holes in it
- A wall with no size in it
- Elements that do not stay constant
- Equal areas in equal times, which is angular momentum in disguise
- Every orbit one force allows, and the number that picks between them
- Five directions and no distance among them
- Nine dates for every surface in the solar system
- Ninety-nine per cent of the mass and none of the spin
- No planet has an eccentricity of its own
- One equation for the speed anywhere, and the eccentricity is not in it
- One time of flight and five ways round
- Only two force laws let an orbit come back
- Six numbers that fix an orbit for all time, and the sixth is the awkward one
- The average depends on what is being averaged
- The bound that holds only in the linear theory
- The craters that were not primary
- The drag that sorts a disc by size
- The elements that stop existing
- The formula that exists, and is not used
- The law that links period to size, and weighs everything
- The one solve that does not ask which conic it is
- The orbit is an ellipse, and the Sun is not in the middle of it
- The orbit that has no period
- The position that has no formula, and is computed anyway
- The precession that switches the cycle off
- The series that is subtracted
- The singularity that is a change of variable
- The table that is a fit
- The third law is wrong by the mass of the planet
- The third thing that is conserved
- The wall that angular momentum builds
- The well moves, and the body keeps its share of it
- Three observations and no orbit at all
- Three rotations that put an orbit in space, and they do not commute
- Two places and a clock decide the path
- Where a planet is and where it is seen
- Where the mass is and where the light is
- Which direction moves which element
- A wall measures a ratio, and a ratio is a line
- Two damping times, one crossing, and the slope that separates them
- A split that decides whether the piece can leave
- A spin barrier with a corner in it