---
title: "Halley’s Comet Redux"
type: "article"
slug: "halleys-comet-redux"
url: "http://localhost/article/halleys-comet-redux/"
markdown_url: "http://localhost/article/halleys-comet-redux.md"
published_at: "2022-09-14T02:41:25+00:00"
modified_at: "2024-05-26T13:09:53+00:00"
featured_image:
  url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg"
excerpt: "Short program that plots the orbit of Halley's Comet, starting in 1986. Typed in by Tim Swenson."
category:
  - name: "CATS Newsletter"
    slug: "cats-newsletter"
    taxonomy: "category"
    url: "http://localhost/category/periodicals/cats-newsletter/"
post_tag:
  - name: "TS 2068"
    slug: "ts2068"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts2068/"
  - name: "Type-in program"
    slug: "type-in-program"
    taxonomy: "post_tag"
    url: "http://localhost/tag/type-in-program/"
model:
  - name: "Timex/Sinclair 2068"
    slug: "ts-2068"
    taxonomy: "model"
    url: "http://localhost/model/ts-2068/"
indiv:
  - name: "Roald Schrack"
    slug: "roald-schrack"
    taxonomy: "indiv"
    url: "http://localhost/indiv/roald-schrack/"
publication_r:
  id: 35941
  title: "CATS Newsletter"
  type: "periodical"
  url: "http://localhost/periodical/cats-newsletter/"
authors: "Roald Schrack"
volume: "4"
issue: "3"
issues_articles:
  - id: 39614
    title: "CATS v4 n3"
    type: "issue"
    url: "http://localhost/issue/cats-v4-n3/"
pages: "7"
pubdate: "June 1986"
archive_link: false
article_media:
  - id: 51939
    title: "Halley’s Comet"
    type: "computer_media"
    url: "http://localhost/computer_media/halleys-comet/"
---

# Halley’s Comet Redux

Short program that plots the orbit of Halley’s Comet, starting in 1986. Typed in by Tim Swenson.

## Source Code: Halley’s Comet

```
    1 REM Halley's Comet Redux
    2 REM Roald Schrack
    3 REM CATS Newsletter v4 n3
    4 REM https://archive.org/details/cats-newsletter/CATS%20v4%20n3%20Jun%201986/page/7/mode/1up
    5 REM Typed by Tim Swenson
   10 REM ** Halley's Comet **
   50 CLS 
   60 CIRCLE 10,85,1
  100 FOR j=1 TO 6
  110 READ n$,p,r
  120 LET pz=p
  130 LET p=-p
  140 LET x=r*COS p+10
  150 LET y=r*SIN p+85
  160 PLOT x,y
  170 IF p>pz THEN GO TO 200
  180 LET p=p+3/r
  190 GO TO 140
  200 PRINT AT 22-y/8,x/8;n$
  210 NEXT j
  220 DATA "E",3.14,7,"J",1.73,31,"S",1.48,58,"U",.82,116,"N",.49,180,"p",.37,234
  230 LET tz=0
  240 LET p=0
  245 PRINT AT 20,1;"It is ";1986;". Halley's comet is"
  250 LET p=p+.008
  260 LET t=12.12*(p-.9673*SIN p)
  270 IF t>tz+1 THEN GO TO 290
  290 LET x=107.4*(.9673-COS p)+10
  300 LET y=27.2*SIN p+85
  302 IF p>6.28318 THEN STOP 
  304 LET d=15.6E6*SQR ((x-10)*(x-10)+(y-85)*(y-85))
  306 PRINT AT 21,1;d;" miles from the sun"
  310 PLOT x,y
  312 IF t>tz+1 THEN GO TO 320
  315 GO TO 250
  320 PRINT AT 20,7;tz+1987
  330 LET tz=tz+1
  340 GO TO 250
```