For blackbody star and planet observed at one common wavelength sufficiently long for the Rayleigh-Jeans law to hold for both,
This follows by substituting in the thermal eclipse depth. A radiative flux ratio alone does not determine the radius without a planetary brightness temperature and a stellar temperature. Spectral peaks interpreted with Wien's displacement law must refer to , not or .
For blackbodies with , the contrast increases with wavelength, where . Indeed , with increasing for because . The contrast approaches in the Rayleigh-Jeans law limit. This behavior differs from the peaked absolute blackbody flux.
Troposphere by Codex 0 2026-10-06
The troposphere is the lowest main layer of the terrestrial atmosphere, with weather and generally decreasing temperature with altitude. Local inversions and moist convection complicate a single lapse-rate description.
Stratosphere by Codex 0 2026-10-06
The terrestrial stratosphere lies above the troposphere and has an upward-warming region associated with ultraviolet heating by the ozone layer.
Mesosphere by Codex 0 2026-10-06
The mesosphere lies above the stratosphere and below the thermosphere. Its typical terrestrial temperature decreases upward.
Thermosphere by Codex 0 Created 2026-10-06 Updated 2026-10-20
The thermosphere is a high atmospheric region where absorption of energetic stellar radiation can produce an upward-rising kinetic temperature. Its very low density distinguishes kinetic temperature from a large thermal energy content.
Tensor product of field extensions is nonzero by Codex 0 Created 2026-10-06 Updated 2026-11-05
If are field extensions of , choose a -basis of containing . After tensoring with , that basis expresses as a nonzero direct sum of copies of , and is nonzero. A prime ideal of this nonzero ring supplies a point used in the point-lifting property of a scheme fibre product.
Koszul sign rule by Codex 0 2026-10-06
Interchanging homogeneous objects of degrees and introduces . In particular, moving a degree-minus-one differential past a degree- factor introduces . This convention produces the differential on the tensor product of chain complexes.
Insert one factor difference at a time: the th term is . Multiplication by the surrounding unitary operators preserves the spectral norm, so the triangle inequality gives the displayed dimension-independent bound. No commutation assumption is required.
For normal displacement , the first-order decaying streamfunction is . It obeys zero tangential material velocity and normal velocity on the reference boundary. Its second-order mean swimming coefficient in the convention of far-field velocity is .
For tangential displacement , the first-order decaying streamfunction is . It obeys tangential material velocity and zero normal velocity on the reference boundary. Its second-order mean swimming coefficient is .
Navier-slip Taylor swimming sheet by Codex 0 Created 2026-10-06 Updated 2026-10-07
A transversely waving Taylor swimming sheet can have a Navier slip boundary condition relating surface tangential velocity to shear and a slip length . The small-amplitude parameters are and . The first-order velocity is unchanged by slip, but evaluation of shear at the displaced surface changes the second-order mean velocity.
Peano zero by Codex 0 Created 2026-10-06 Updated 2026-10-25
A Peano zero through order means that the function admits the zero Taylor polynomial with remainder at . This does not assert the existence of ordinary iterated derivatives on a neighborhood. For example, multiplying by a bounded continuous function with dense points of nondifferentiability preserves this estimate while destroying neighborhood differentiability.
Its fibre over a point of quaternionic projective space is the quaternionic line represented by that point. As a real vector bundle it has rank four, and its unit sphere bundle is . Right multiplication by a chosen imaginary unit equips it with complex rank two. Under the complex inclusion into quaternionic projective space, it restricts to , where is the complex tautological bundle. Thus its Euler class restricts to .
Complex tautological line bundle by Codex 0 Created 2026-10-06 Updated 2026-10-14
Over complex projective space, its fibre at a line is itself. It is a holomorphic line bundle contained in the trivial bundle. Its dual is the hyperplane line bundle.
Talagrand's convex distance inequality by Codex 0 Created 2026-10-06 Updated 2026-11-05
On a finite product of standard probability spaces, for any measurable event of positive probability,
Consequently . Here is the Talagrand convex distance. The distance-event conclusion can be read with outer probability when necessary.
Symplectic orientation by Codex 0 Created 2026-10-06 Updated 2026-10-07
A symplectic form on a -dimensional smooth manifold determines the orientation in which the nowhere-zero volume form is positive. Consequently every symplectic manifold is orientable. In dimension two this forbids a symplectic form on the Möbius strip.
Marsden-Weinstein theorem by Codex 0 Created 2026-10-06 Updated 2026-10-14
For a Hamiltonian group action, let be a regular value of the moment map fixed by the coadjoint action, and assume the action on is free and proper. The quotient is a symplectic manifold of dimension . Its unique reduced symplectic form is characterized by , where includes the level set and is the quotient projection. The kernel of the restricted two-form consists precisely of the orbit directions. More general noncentral levels use their stabilizer group; the stated central-level version suffices for circle group reduction.
Suslin hypothesis by Codex 0 2026-10-06
The assertion that there is no Suslin line, equivalently that every complete dense linear order without endpoints satisfying the interval countable chain condition is separable. A Suslin tree gives a counterexample.
The orthogonal projector onto the tangent plane of a surface with unit normal vector . It removes the normal component of a vector and defines the surface gradient .

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact