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
Graduate Calculating the age of the universe without a model?
- wabbit
- · Replies 24 ·
Graduate Sublimation temperature of water in vacuum = 150K ?
- Qshadow
- · Replies 18 ·
Graduate Spectroscopic system, AB magnitudes
- sketos
- · Replies 2 ·
Undergrad Is the universe truly expanding?
- tressure
- · Replies 83 ·
Undergrad Why is the speed of light 186,000 miles per second?
- thejun
- · Replies 37 ·
Graduate Equation involving H and a re Accerlerating Universe
- Buzz Bloom
- · Replies 8 ·
Undergrad Difference between a red giant and red supergiant?
- 21joanna12
- · Replies 4 ·
Graduate Stefan-Boltzmann law, luminosity, brightness and magnitude?
- 21joanna12
- · Replies 2 ·
Graduate Why do toddlers have a logarithmic understanding of numbers?
- Petahanks
- · Replies 11 ·
Undergrad Was Space Present Before the Big Bang?
- tressure
- · Replies 13 ·
Undergrad SDP.81 : how do we see the gavitational lens?
- maajdl
- · Replies 2 ·
Undergrad If all time happens at once, why is the universe expanding?
- Hunter Brandon
- · Replies 13 ·
Graduate Are atomic energies increasing as the Universe expands?
- jcap
- · Replies 2 ·
Undergrad Does extreme gravitational time dilation make travelers age slower than Earth?
- RM Isco
- · Replies 3 ·
Favorite Prominent / Professional Astrophotographers
- excelsior
- · Replies 2 ·
Graduate Did the universe have a begining?
- wolram
- · Replies 9 ·
Graduate How is dark energy density calculated from cosmic observations?
- Quarlep
- · Replies 16 ·
High School Does space-time have an energy itself?
- Quarlep
- · Replies 59 ·
Graduate How fast does the sun's radius grow during its red giant phase?
- JohnPrior3
- · Replies 8 ·
Graduate Should the concept of Falsifiability be abandoned in science?
- wolram
- · Replies 22 ·
Graduate Why are there stars that are "older than the universe"?
- jack476
- · Replies 4 ·
Graduate Cosmological vs. Relativistic Doppler Shift
- thrush
- · Replies 4 ·
Undergrad Why does the sun's hour angle change so little over 23 days?
- Frank Einstein
- · Replies 4 ·
High School Constant acceleration of gravity
- quincy harman
- · Replies 2 ·
Graduate When did relic neutrinos cease being relativistic?
- GeorgeDishman
- · Replies 4 ·
High School Understanding Gravitational Pull and Its Effects on Humans
- yuganes warman
- · Replies 12 ·
Graduate Total energy of two merging elliptical galaxies
- jl29488
- · Replies 8 ·
Graduate Explanation for similar structures at different scales
- Jimster41
- · Replies 2 ·
Undergrad What is the scale factor R(t) in cosmology?
- scoopaloop
- · Replies 7 ·
Graduate Is Dark Energy a Misinterpreted Phenomenon?
- Allan R.
- · Replies 10 ·
Graduate Julian Ephemeris Date from Ephemeris Time
- Philosophaie
- · Replies 1 ·
Undergrad What's the nothingness that our universe is expanding into?
- Meron
- · Replies 76 ·
Graduate Gravitational entropy in the early universe
- Khashishi
- · Replies 7 ·
Graduate What is the relationship between orbital semi latus rectum and angular momentum?
- Penguinluons
- · Replies 3 ·
Undergrad Why does the Sun behave like a black body?
- resurgance2001
- · Replies 32 ·
Graduate Bending of space and time, is it true?
- AshUchiha
- · Replies 71 ·
Graduate How Can We Harness the Power of Space Elevators and Atmospheric Electricity?
- Mk
- · Replies 7 ·
Graduate Black holes in the globular cluster M22 with Dr. Tom Maccarone
- liometopum
- · Replies 12 ·
Graduate Calculating Surface Density of the Universe Using the Shell Model
- Quarlep
- · Replies 7 ·
Undergrad What does it mean that the universe looks the same in all directions?
- pvk21
- · Replies 44 ·
High School Why does Mercury appear out of alignment with other planets in Stellarium?
- Frank Einstein
- · Replies 12 ·
Graduate Size of observable vs UN-observable Universe, etc
- Stan Stuchinski
- · Replies 3 ·
Graduate What can you learn about cosmology from Google calculator?
- marcus
- · Replies 111 ·
Stargazing Can a segmented kilometer-wide telescope with rotating arms work?
- RKOwens
- · Replies 14 ·
Graduate Scientific importance of total Solar eclipses?
- tarquinius
- · Replies 10 ·
Graduate Could igniting Titan's methane oceans create a habitable atmosphere?
- bennyschmidt
- · Replies 34 ·
High School Do we all belong to the same star?
- Yashbhatt
- · Replies 7 ·
Graduate Role of quantum mechanics in cosmology
- pvk21
- · Replies 11 ·
Graduate Cold dark matter versus warm dark matter at galactic scales
- wolram
- · Replies 5 ·
Graduate Boltzmann equation Kinetic equilibrium (Dodelson)
- center o bass
- · Replies 1 ·
Undergrad Proof to Kepler's first and second laws
- Shahar
- · Replies 3 ·
Graduate Analogy for recession of galaxies > the speed of light
- osotou
- · Replies 8 ·
Stargazing Why don't secondary mirrors create shadows in reflecting telescopes?
- 21joanna12
- · Replies 6 ·
Undergrad How wide is the observable horizon, at sea level?
- Lonious
- · Replies 10 ·
Graduate High redshift galaxies in the HUDF
- sketos
- · Replies 1 ·
Graduate Fundamental Relationship Between Time and Space Derivatives
- ElectricKitchen
- · Replies 6 ·
Undergrad What is the center of a globular clusters made of?
- vrmuth
- · Replies 50 ·
Graduate Why must a collapsing gas cloud continuously lose energy to form a star?
- thegirl
- · Replies 5 ·
Graduate Our universe as an expanding sponge that is constantly falling.
- Shu Sheng
- · Replies 6 ·
Graduate Do M or string theory imply a lower limit to size?
- slatts
- · Replies 4 ·
Graduate Physical basis for exoplanet size and temperature classification
- lpetrich
- · Replies 6 ·
Undergrad How Can We Reach Habitable Exoplanets?
- cjackson
- · Replies 8 ·
Graduate Supernova prediction: SN Refsdal
- mfb
- · Replies 1 ·
Undergrad Exoplanet Eccentricity vs Orbital Period
- Drakkith
- · Replies 5 ·
Undergrad Saturn's day is 6 minutes shorter than previously measured
- CygnusX-1
- · Replies 4 ·
Is the Hubble Telescope Smiling at a Gravitational Lens?
- Andy Resnick
- · Replies 12 ·
Stargazing How Do Lasers Work in Telescopes to Capture Images of the Universe?
- pvk21
- · Replies 3 ·
High School Fake magnification and other information
- sauroman1
- · Replies 6 ·
Graduate Redshift of supernova light curve
- jcap
- · Replies 10 ·
Stargazing Understanding the Field of View of Reflecting and Refracting Telescopes
- 21joanna12
- · Replies 9 ·
Graduate Question on possible dark matter classification
- aademarco
- · Replies 9 ·
Undergrad Which stellar layer produces the observed spectral lines
- 21joanna12
- · Replies 3 ·
Graduate Feedback and equilibrium between black holes and galaxies
- Tanelorn
- · Replies 4 ·
Graduate How can you show the CMB shift parameter?
- shadi_s10
- · Replies 7 ·
I got a bad feelin' about this Chewie turn us around
- DaveC426913
- · Replies 4 ·
Stargazing Is an astronomical telescope only a refracting telescope?
- 21joanna12
- · Replies 3 ·
Graduate Covariance between scalar amplitude and spectral index in Planck data
- thecommexokid
- · Replies 2 ·
Graduate Do quasar jets spiral into galaxy formation?
- twisted-outcast
- · Replies 3 ·
Graduate Why is vacuum energy 10^100 times larger than the cosmological constant?
- Quarlep
- · Replies 5 ·
Graduate What does a temporally infinite universe imply?
- slatts
- · Replies 1 ·
Graduate Could a Collapsing Black Hole Be the Origin of Our Universe?
- Shu Sheng
- · Replies 9 ·
Stargazing Viewing stars through a refracting telescope?
- 21joanna12
- · Replies 2 ·
High School Are Jupiter's bands visible with binoculars?
- Glenstr
- · Replies 17 ·
Graduate What supported the singularity during the Big Bang?
- Bray420
- · Replies 7 ·
Orion and Comet Lovejoy images from Arizona, February 2015
- spark802
- · Replies 4 ·
Undergrad Why is the universe considered to be flat?
- Meron
- · Replies 3 ·
Graduate Supernova Explosion near a black hole
- Ravi Prakash
- · Replies 7 ·
High School Measuring Light Years: How Far Is the Andromeda Galaxy?
- JustATheory
- · Replies 3 ·
Graduate Entire universe ending with a supermassive black hole?
- Shu Sheng
- · Replies 10 ·
Graduate Static universe, spacetime and the stress-energy tensor
- timmdeeg
- · Replies 13 ·
Undergrad What does "the big bang happened everywhere at once" mean?
- CaptDude
- · Replies 154 ·
Graduate How do scientists estimate the total energy of the universe?
- Quarlep
- · Replies 15 ·
Graduate What are P-branes and D-branes in string theory?
- Quds Akbar
- · Replies 5 ·
Graduate Dark energy and the Cosmological Constant
- Quds Akbar
- · Replies 37 ·
Did You Capture the March 17 Aurora Borealis?
- spark802
- · Replies 2 ·
Graduate How do you draw eccentric anomaly and mean anomaly?
- Philosophaie
- · Replies 2 ·
Solar eclipse on March 20, 2015 with 98% coverage in Scotland
- Garth
- · Replies 13 ·
Feeling insignificant after watching space movies
- HomogenousCow
- · Replies 10 ·
Undergrad Are multiple universes astronomy or philosophy?
- richard9678
- · Replies 46 ·
Undergrad Why are the more distant galaxies/stars moving faster away?
- Kiyal
- · Replies 29 ·