Join in expert discussion on the topics of Astronomy, astrophysics and cosmology. This may include discussion on celestial objects, space, and the physical universe as a whole. Mainstream science only.
Threads
High School Can particles interact without a mass?
- nonamebrand
- · Replies 36 ·
High School Do Atoms Expand with the Universe?
- Tayler
- · Replies 76 ·
Undergrad Why does particle physics predict cosmo constant is 10^120 too big?
- swampwiz
- · Replies 13 ·
Undergrad N-body simulation of high or low-mass dark matter particles
- Ranku
- · Replies 4 ·
Undergrad Dark matter and structure formation
- Ranku
- · Replies 4 ·
Undergrad An apparently obscure question re dark matter
- Buzz Bloom
- · Replies 12 ·
Undergrad Is the supply of the observable CMB radiation limited?
- JimJCW
- · Replies 50 ·
Undergrad Dark Sky Parks -- coming to a park near you
- berkeman
- · Replies 1 ·
Graduate Can stellar structure models predict the Sun's radius from first principles?
- thepolishman
- · Replies 15 ·
High School What is the Universe expanding into?
- Akshaya dhakal
- · Replies 5 ·
High School Some visuals for Size of Solar System, Galaxy, Universe
- Tom.G
- · Replies 3 ·
Undergrad (See image) At what distance does the temperature of the Corona decline?
- smithpa9
- · Replies 2 ·
Undergrad What would be the geological consequences of a "big crunch"?
- SEYED2001
- · Replies 9 ·
Graduate Single photon avalanche detector (SPAD) difficulties with photometer
- Benschu
- · Replies 2 ·
Undergrad What would be the geological events during a "big slurp"?
- SEYED2001
- · Replies 11 ·
Undergrad Granules On The Sun: Photosphere Or Convection Zone?
- smithpa9
- · Replies 2 ·
Undergrad Energy-momentum tensor as energy density
- Ranku
- · Replies 6 ·
Undergrad Are orbital resonances constructive or destructive?
- smithpa9
- · Replies 1 ·
High School Observing Orbital Mechanics from the 2nd Focus of Earth's Orbit
- Dustin Maki
- · Replies 8 ·
Undergrad Magnetism and Gravity Discussion/Questions
- Sterkx
- · Replies 15 ·
Undergrad Universe re-collapse and time reversal
- Ranku
- · Replies 14 ·
High School Why was the Sun's output not as intense in the past?
- PainterGuy
- · Replies 7 ·
Undergrad How do astronomers find exoplanets around distant stars?
- thegroundhog
- · Replies 9 ·
High School Spacetime: The cause of matter?
- Buckethead
- · Replies 2 ·
Undergrad Infinite space in a finite bubble, in a Tegmark Level 2 multiverse?
- DanielJ2021
- · Replies 3 ·
High School How can we watch BHs collide in a finite time?
- Paige_Turner
- · Replies 18 ·
High School Star visible for longest time from Earth
- Nathi ORea
- · Replies 6 ·
Undergrad Can relativistic matter exist at absolute zero?
- James William Hall
- · Replies 2 ·
Undergrad How do we know that red-shift is caused by expansion?
- tkyoung75
- · Replies 12 ·
Stargazing Is the Hubble Space Telescope Dead?
- russ_watters
- · Replies 12 ·
Graduate How do we differentiate the K-corona from the F-corona?
- carlos-carlos
- · Replies 1 ·
Graduate How Can I Filter Known Globular Clusters in SDSS Data?
- mancini
- · Replies 1 ·
Graduate NASA’s InSight Mission Reveals Internal Structure of Mars
- Astronuc
- · Replies 0 ·
High School Do emission nebula glow because of ionised or excited electrons?
- Nathi ORea
- · Replies 4 ·
Undergrad Will the number of visible galaxies vanish in ΛCDM?
- mbond
- · Replies 11 ·
Undergrad Does matter entering a black hole violate conservation of energy?
- DaveL1881
- · Replies 9 ·
Graduate Is the CMBR interpretation for dark matter a fudge?
- Adrian59
- · Replies 35 ·
Undergrad Questions about Density Parameter and Critical Density
- pdm
- · Replies 6 ·
Undergrad Red-Shifting vs. Luminosity Question
- yotta
- · Replies 3 ·
High School What happens if Earth falls into the Sun?
- Paige_Turner
- · Replies 15 ·
Stargazing Could Elon Musk's Starlink orbitals piggyback telescopes?
- Gfellow
- · Replies 6 ·
High School The Impact of Tidal Force on a Star's Magnetic Field and Supernova
- Paige_Turner
- · Replies 1 ·
High School Does gravitational time dilation change the speed of light in outer space?
- jeremyfiennes
- · Replies 32 ·
Graduate Relationship between energy density and cosmological constant
- novice_hack
- · Replies 7 ·
Graduate Did the Universe Begin as Pure Energy?
- mathman
- · Replies 6 ·
High School Biggest asteroid to pass Earth in 2021
- minoss
- · Replies 1 ·
Undergrad Rotation curve with neutral hydrogen and dark matter
- Ranku
- · Replies 7 ·
Undergrad Particle and Event Horizons in the ΛCDM Model
- JimJCW
- · Replies 19 ·
High School Questions about dark matter, matter and elements
- Matias
- · Replies 7 ·
Undergrad The Acceleration and the density of galaxies
- mbond
- · Replies 5 ·
High School How the Hubble constant determines the universe's age and future expansion
- Mike holden
- · Replies 3 ·
High School Betelgeuse unusual dimming - what's up?
- Astronuc
- · Replies 60 ·
Undergrad Slow-roll Inflation and Horizon Problem
- AHSAN MUJTABA
- · Replies 1 ·
High School Light Leaving Earth-Observer's View of Events in Time
- happyhacker
- · Replies 8 ·
Undergrad Dimensions of Cosmic Scale Factor ##a(t)##
- AHSAN MUJTABA
- · Replies 10 ·
Graduate Relation between Matter Power spectrum and Angular power spectrum
- fab13
- · Replies 2 ·
Undergrad Why are emission spectra of stars rarely shown?
- pkc111
- · Replies 5 ·
High School Why can we only see one side of the moon?
- AEinstein1921
- · Replies 13 ·
Undergrad What is the average annual accumulation of cosmic dust on Earth?
- swampwiz
- · Replies 3 ·
High School Looking for Simulations of Exoplanets
- cindersky
- · Replies 4 ·
Graduate Expression of the mean and variance of spectroscopic Shot Noise
- fab13
- · Replies 6 ·
High School What happens to time as space is expanding?
- AlfSalte
- · Replies 68 ·
Undergrad Temperature of the Universe based on the ΛCDM Model
- JimJCW
- · Replies 4 ·
Undergrad Can a Homogeneous Universe Avoid a Big Crunch?
- GoToLoop
- · Replies 28 ·
Undergrad Implications if New Dark Matter Maps are Correct?
- Jarvis323
- · Replies 9 ·
High School Cosmological constant for the Universe's expansion
- jeremyfiennes
- · Replies 5 ·
Undergrad If Jupiter had a 5th large moon until "recently", would we know?
- xpell
- · Replies 4 ·
Graduate New Dark Energy Map Challenges Einstein's Theory
- saddlestone-man
- · Replies 2 ·
Undergrad Andromeda vs. Milky Way galaxies
- bbbl67
- · Replies 30 ·
Undergrad What is theoretically the heaviest isotope that the R-process could produce?
- swampwiz
- · Replies 11 ·
Graduate Cosmological gravitational waves
- etotheipi
- · Replies 9 ·
Undergrad Planetary orbits - the 2-body problem
- dyn
- · Replies 84 ·
High School Seeing a half Moon - where is the Sun?
- Tayler
- · Replies 19 ·
Stargazing Lightning ball - me to analyze this rare video
- Toreno
- · Replies 42 ·
Undergrad FRBs (Fast Radio Bursts) -- New clues of their location and origin
- Tom.G
- · Replies 0 ·
High School Could an Extraterrestrial Object Near Earth Disrupt Satellites?
- happyhacker
- · Replies 5 ·
Undergrad H0LiCOW quasar lensing measures Hubble constant at 73.3 km/(s·Mpc)
- mfb
- · Replies 29 ·
Graduate Fourier transform and Cosmic variance - a few precisions
- fab13
- · Replies 4 ·
High School Feasibility of multiple "big bangs"
- MikeeMiracle
- · Replies 5 ·
Stargazing Could macroscopic dark matter trigger lightning strikes?
- TurtleMeister
- · Replies 16 ·
Undergrad Dark energy is intrinsic to the space itself
- PainterGuy
- · Replies 5 ·
Graduate Polling for estimates of probability our universe is infinite
- Buzz Bloom
- · Replies 1 ·
Undergrad Is the interior diameter of a black hole infinite if space stretches to the singularity?
- Johan0001
- · Replies 36 ·
Undergrad Freshly Made Plutonium From Outer Space Found On Ocean Floor
- Keith_McClary
- · Replies 2 ·
High School The Fate of the Universe -- Expansion or Collapse?
- stilt
- · Replies 5 ·
Undergrad Why do we distinguish spacetime curvature from spatial curvature?
- Ranku
- · Replies 18 ·
Insights Do Black Holes Really Exist? - Comments
- PeterDonis
- · Replies 73 ·
Undergrad Proton decay at the end of the Universe
- Gary Menzel
- · Replies 13 ·
Undergrad How fast must Voyager travel to leave the solar system?
- SPB COOPERATOR
- · Replies 4 ·
High School Why Do We See Darkness in a Universe Full of Stars?
- Joe30174
- · Replies 15 ·
Undergrad The Hubble constant − constant in what way?
- JimJCW
- · Replies 18 ·
Undergrad How long would it take the Universe to generate an Earth-like chemistry?
- BillTre
- · Replies 8 ·
Undergrad Why does mass of observable universe match distance squared in early universe model?
- dedocta
- · Replies 5 ·
Undergrad Spatial flatness and cosmological constant
- Ranku
- · Replies 5 ·
Graduate Why are B mode values used to disfavor power law potentials in Planck 2015?
- JD_PM
- · Replies 1 ·
Graduate Patterns in extragalactic stellar trajectories near the Milky Way
- Prez Cannady
- · Replies 2 ·
Undergrad Are some cosmic rays iron nuclei?
- swampwiz
- · Replies 7 ·
Undergrad Changing curvature as a universe evolves
- Will Learn
- · Replies 36 ·
Undergrad What happens to the material not involved in the core collapse of a supernova?
- MarkL
- · Replies 4 ·
High School Vertical lift question (Lift a roof from beneath with limited space)
- Kelly1214
- · Replies 10 ·