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 The Space Between Atoms -- Teaching Middle School
- leeone
- · Replies 37 ·
Undergrad Does the sun always rise to the right of magnetic north on any planet?
- jjustinn
- · Replies 6 ·
High School UFO or Dead Pixel? What's Flying Across the Moon?
- B0b-A
- · Replies 9 ·
Undergrad Why does space expansion cause redshift?
- ricardo81
- · Replies 43 ·
Undergrad Why do the constellations appear to move differently in different seasons?
- Pjpic
- · Replies 6 ·
Graduate BH to Sun, back of the napkin calculation of solar mass
- elegysix
- · Replies 6 ·
Undergrad How can we say space is expanding if galaxies are just moving apart?
- ggolu2
- · Replies 7 ·
Graduate How/why are pocket universes created during eternal inflation?
- phyguuy
- · Replies 39 ·
Graduate Zero-point energy density evaluation
- Helios
- · Replies 19 ·
Graduate SGP4 propagation of ISS TLE showing incorrect altitude and date
- thor36
- · Replies 1 ·
Undergrad Can a planet with a thin atmosphere have oceans?
- willstaruss22
- · Replies 23 ·
Graduate Which Stars Cast the Milky Way's First Light?
- CygnusX-1
- · Replies 3 ·
Graduate Stars that look older than the universe
- wolram
- · Replies 5 ·
High School Finding M31 from light-polluted suburbs with a 6SE telescope
- Ritzycat
- · Replies 10 ·
Graduate Question regarding to acceleration in the rate of expansion of our cosmos
- aditya ver.2.0
- · Replies 3 ·
Graduate Is CNO cycle more life friendly than H->He?
- tzimie
- · Replies 23 ·
Easy astronomical objects to see from the city
- Greg Bernhardt
- · Replies 14 ·
ISS Visibility If Painted Black?
- Quantula
- · Replies 4 ·
Undergrad What is the Density Change Towards the Centre of a Gas Giant?
- Laser212
- · Replies 2 ·
Graduate Sinking instead of expanding universe?
- Rolf
- · Replies 23 ·
Andromeda Galaxy image
- spark802
- · Replies 4 ·
Graduate FRW pertubations in overdense and underdense regions
- center o bass
- · Replies 1 ·
Undergrad Would the sky be red if the atmosphere was thicker?
- willstaruss22
- · Replies 9 ·
Graduate Non equilibrium boson distribution function
- center o bass
- · Replies 1 ·
Graduate If the sun becomes a black hole will its schwarzschild radius change?
- avito009
- · Replies 2 ·
Undergrad What is the significance of the foci in gravitational orbits?
- MattWakes
- · Replies 2 ·
Undergrad Which Has A Stronger Gravitational Pull - A Black Hole or Neutron Star?
- Uberhulk
- · Replies 5 ·
High School I saw the 23 Oct 2014 N America partial solar eclipse
- lpetrich
- · Replies 2 ·
Graduate Why two terms "Dark Energy" and "Dark Matter"
- atuldpatil
- · Replies 2 ·
"Churning galaxy boasts a fiery halo of baby stars"
- Spinnor
- · Replies 1 ·
Graduate How do photons lose energy as spacetime expands?
- anorlunda
- · Replies 9 ·
High School Trying to understand the universe .possible at 13 years old?
- canutej
- · Replies 12 ·
Graduate White dwarf mass-radius relationship
- MattWakes
- · Replies 7 ·
High School Boundaries between the Constellations
- Philosophaie
- · Replies 2 ·
Graduate Can black holes hold the key to the origin of our universe?
- wolram
- · Replies 1 ·
Graduate Origin of our universe 4D black hole
- StonedPhysicist
- · Replies 33 ·
Undergrad Were all galaxies quasars when they were young?
- Robin
- · Replies 2 ·
Graduate Can axions explain dark matter?
- Tanelorn
- · Replies 19 ·
High School Why does the moon rise at different times and directions for different phases?
- ajay.05
- · Replies 3 ·
Undergrad Calculating CME particle speed from SOHO images
- SigmaOctans
- · Replies 4 ·
Graduate How is the Rotational Velocity of Galaxies Measured?
- ChrisVer
- · Replies 3 ·
Graduate Why do large elliptical galaxies not collapse due to their gravity?
- Tanelorn
- · Replies 8 ·
Undergrad Does infinite space mean the Big Bang can't create the whole universe?
- DHooley
- · Replies 16 ·
Graduate Does cosmic time (or comoving clock) run at the same pace at all times?
- Vincentius
- · Replies 23 ·
Undergrad How Stars Ignite - The Fusion Reaction
- avito009
- · Replies 13 ·
Graduate Are High Z SNe Brighter than LCMD Predicts?
- RCopernicus
- · Replies 1 ·
Graduate Current Research on Communication Between Universes?
- Mandy mae
- · Replies 8 ·
Undergrad Determine the least value of declination of stars so that stars can be seen?
- nicolauslamsiu
- · Replies 3 ·
Graduate Can a Balloon Float Inside a Hollow, Air-Filled Space Elevator?
- udtsith
- · Replies 4 ·
Graduate Why do black holes vanish over time?
- NTW
- · Replies 16 ·
Undergrad What's the scale on Mars rover "Microscopic Imager" images ?
- B0b-A
- · Replies 2 ·
Graduate Measuring Cosmic Rays: There's an App for that
- TumblingDice
- · Replies 1 ·
High School Uranus' closest approach to earth and its interval
- BOAS
- · Replies 4 ·
Graduate What exactly is the Hubble parameter?
- 21joanna12
- · Replies 7 ·
Undergrad Kepler's 3rd law with solar masses and units
- mh8780
- · Replies 3 ·
Graduate Dark Matter does not exist, what do you think?
- wolram
- · Replies 59 ·
Graduate Lagrange Point and orbital velocity
- _Stew_
- · Replies 2 ·
What would you do if you were in space
- Mitxigan
- · Replies 1 ·
Undergrad How can light not escape black holes if it's the speed limit?
- CKaiser1985
- · Replies 9 ·
Questions about the expansion of the universe
- ocset
- · Replies 3 ·
Graduate Is the universe NOT accelerating ?
- fencewalker
- · Replies 5 ·
Graduate Proof that black holes do not destroy information
- Ipquarx
- · Replies 2 ·
High School What is the current state of the solar cycle?
- !Jon Snow!
- · Replies 5 ·
Undergrad How can I determine right ascension and declination of a star in the sky?
- r m williams
- · Replies 4 ·
Total Lunar Eclipse 8th Oct 2014
- davenn
- · Replies 23 ·
Graduate What problems does cosmic inflation actually solve beyond fine tuning?
- CKH
- · Replies 41 ·
Stargazing Using a geostationary satellite as a mirror receiver for a ground-based telescope
- gaurav0751
- · Replies 10 ·
Graduate What is the Visible Mass of the Milky Way?
- RCopernicus
- · Replies 4 ·
Graduate Where did primordial density perturbations that seeded galaxies come from?
- wolram
- · Replies 29 ·
Graduate Does opening a hatch outward impart force to the spacecraft?
- Prof Null
- · Replies 13 ·
Graduate How do ULXs escape black holes if they travel faster than light?
- Dryson
- · Replies 6 ·
Graduate Is Dark Matter Only Interacting Through Gravity or Are There Other Theories?
- Ciro Spaciari
- · Replies 19 ·
Graduate Can There Be Time Without Space? A Question for Discussion
- iDimension
- · Replies 3 ·
Graduate Stefan-Boltzmann law vs assumptions in exoplanet habitability calculations
- |Glitch|
- · Replies 15 ·
Graduate Why does light travel radially in the FRW universe?
- center o bass
- · Replies 5 ·
Graduate Is there an unseen part of the universe older than the known universe?
- cjackson
- · Replies 3 ·
Graduate Big Bang, big rip, lQc, has anyone ever run a computer simulation?
- yoda-morpheus
- · Replies 5 ·
Undergrad Introdutions to mathematical astronomy?
- moriheru
- · Replies 1 ·
Undergrad Reynolds Number and Turbulence in Atmospheric Boundary Layers
- Martina835
- · Replies 4 ·
Graduate Could the Big Bang be related to the flow of current in vacuum tubes?
- Dryson
- · Replies 7 ·
Graduate Why does inflation generate gravity waves?
- thecommexokid
- · Replies 5 ·
Graduate Was the CMB Radiation Predicted or Post-Dicted by Big Bang Cosmology?
- AdkinsJr
- · Replies 28 ·
Undergrad Does the observable universe support the idea of circular math?
- Physics_Kid
- · Replies 7 ·
Graduate Can a black hole be connected with making a time machine?
- Sandhani Boruah
- · Replies 4 ·
Graduate Dark Matter: Why doesnt dark matter coalesce 'into' Ordinary Matter - Repost
- curiouschris
- · Replies 9 ·
Undergrad What evidence exists of black holes colliding?
- Johan0001
- · Replies 3 ·
Graduate Mass Profile in Elliptical Galaxies
- RCopernicus
- · Replies 1 ·
Graduate Where Is Dark Matter in the Universe?
- curiouschris
- · Replies 15 ·
Graduate I don't believe in singularities
- omegabeta
- · Replies 10 ·
Graduate Relationship between Ultracold neutrons and neutron stars
- skujesco2014
- · Replies 6 ·
Graduate A Question Concerning Solar Flares
- |Glitch|
- · Replies 8 ·
Graduate Are neutrons in a neutron star relativistic?
- skujesco2014
- · Replies 15 ·
Graduate Is the Universe Actually Collapsing Instead of Expanding?
- stefanow
- · Replies 8 ·
Graduate Making basic astro/cosmo calculations easy with google calculator--examples
- marcus
- · Replies 2 ·
Would aging rates differ for humans on other planets?
- ozzlight
- · Replies 4 ·
Graduate Can You Orbit the Photon Sphere Without Being Pulled into the Event Horizon?
- avito009
- · Replies 2 ·
Undergrad Is it accurate to say 99% of the universe is pure black with no sound?
- zeromodz
- · Replies 4 ·
Graduate When Was the Universe's Expansion Rate Zero?
- SteveK2
- · Replies 53 ·
Graduate Dark Energy an effect of inhomogeneity?
- CKH
- · Replies 5 ·
Graduate Beginning of accelerating expansion
- hendoS
- · Replies 3 ·