---
title: "Exoplanet day and night"
description: "Derive planetary heat transport and projected phase curves, replay actual WASP-43b MIRI products, and read the chemistry and cloud evidence."
canonical_url: "https://sandboxphysics.com/stories/planet-phase-curves/"
language: "en"
page_type: "story"
alternate_languages:
  zh-CN: "https://sandboxphysics.com/zh/stories/planet-phase-curves/"
last_modified: "2026-11-03"
---

AC21

# Exoplanet day and night

Sandbox Physics · 2026-10-28

Follow a warm parcel across the evening edge. Calculate how the globe emits, then compare its changing light with a fixed JWST observation.

1. L1

   ## [Seeing day and night on an unresolved planet](https://sandboxphysics.com/stories/planet-phase-curves/dayside-in-starlight/)

   How an unresolved planet reveals its bright dayside and warm nightside through changing infrared light.

2. L1

   ## [The areas that set a planet's temperature](https://sandboxphysics.com/stories/planet-phase-curves/areas-and-temperatures/)

   Derive planetary equilibrium temperatures from intercepted and emitted areas, then distinguish a parcel from a visible hemisphere.

3. L2

   ## [Follow a gas parcel into the night](https://sandboxphysics.com/stories/planet-phase-curves/a-parcel-crosses-night/)

   Follow a gas parcel through heating, advection and nonlinear cooling; derive the thermal timescale and the capacity-flow degeneracy.

4. L3

   ## [Add a globe's light to make a phase curve](https://sandboxphysics.com/stories/planet-phase-curves/from-a-globe-to-a-curve/)

   Derive hemisphere projection, secondary eclipses, Lambert reflection and the brightness-map null space.

5. L3

   ## [Replay the WASP-43b MIRI phase curve](https://sandboxphysics.com/stories/planet-phase-curves/replay-wasp43-miri/)

   Replay fixed WASP-43b MIRI products, propagate a conditional harmonic posterior and examine ephemeris, map and thermal degeneracies.

6. L4

   ## [Read the chemistry, clouds and maps behind a phase curve](https://sandboxphysics.com/stories/planet-phase-curves/clouds-chemistry-and-maps/)

   Read pinned primary papers on hydrogen chemistry, WASP-43b clouds and occultation mapping, following their equations and figures.

[Move the wind and follow its heat](https://sandboxphysics.com/labs/exoplanet-thermal-phase-curve/)

## Sources and calculation scope

1. [Nicolas B. Cowan and Eric Agol, A Model for Thermal Phase Variations of Circular and Eccentric Exoplanets](https://arxiv.org/pdf/1011.0428v1)

   arXiv:1011.0428v1, submitted 2010-11-01. Sections 2–3, equations 1–10; section 4, equation 13; section 6; figures 1 and 6.

2. [Nicolas B. Cowan and Eric Agol, Inverting Phase Functions to Map Exoplanets](https://arxiv.org/pdf/0803.3622v1)

   arXiv:0803.3622v1, submitted 2008-03-25. Section 2, equations 1–4; section 3.2, equation 7; figure 1.

3. [Nicolas B. Cowan and Eric Agol, The Statistics of Albedo and Heat Recirculation on Hot Exoplanets](https://arxiv.org/pdf/1001.0012v2)

   arXiv:1001.0012v2, revised 2010-12-20. Sections 1, 2.1 and 2.2; equation 3.

4. [Nikku Madhusudhan and Adam Burrows, Analytic Models for Albedos, Phase Curves, and Polarization of Reflected Light from Exoplanets](https://arxiv.org/pdf/1112.4476v1)

   arXiv:1112.4476v1, submitted 2011-12-19. Albedo definitions; section 3.1, equation 33 and figure 7; local illumination conventions checked against the hemisphere integral.

5. [Taylor J. Bell and Nicolas B. Cowan, Increased Heat Transport in Ultra-Hot Jupiter Atmospheres Through H2 Dissociation/Recombination](https://arxiv.org/pdf/1802.07725v2)

   arXiv:1802.07725v2, revised 2018-04-09. Sections 2.1–2.3, equations 1–8; figures 1–4.

6. [Taylor J. Bell et al., Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b](https://arxiv.org/pdf/2401.13027v1)

   arXiv:2401.13027v1, submitted 2024-01-23; dataset v1 published 2024-04-30. Main figures 1–4; Methods Observations and Data Reduction, PDF pages 12–21 including spectral binning, shadowed region, harmonics and Eureka v1 equations 1–7; Data Availability, PDF page 33. Published methods also checked for trimming and light-travel convention.

7. [Rodrigo Luger et al., STARRY: Analytic Occultation Light Curves](https://arxiv.org/pdf/1810.06559v1)

   arXiv:1810.06559v1, submitted 2018-10-15. Section 2.4, equation 16; section 3.1, equations 17–20; sections 3.2–3.3; section 4.2 and figure 5.

8. [Taylor James Bell and the 17 other named Zenodo creators, Products and Models for Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b](https://zenodo.org/records/10525170)

   Zenodo record 10525170, v1, published 2024-04-30. Original API metadata, archive directory, selected HDF5 arrays and attributes, S3/S4/S5 configuration and EPF.